Finite Group Databasebeta

← C61×#16262 #29519695

Subgroups — C61×#16262 #29519695

Order 15616.

1798 conjugacy classes of subgroups.

The subgroup lattice has 686 nodes — too large to display as a diagram.

Conjugacy classes of subgroups

#subgroupG/Hclass sizemultiplicitynormal?properties
1C22×C22⋊Q8×C61C211yesmaximal, characteristic
2C2×C61×#397C212yesmaximal
3C2×C61×#395C211yesmaximal, characteristic, complemented
4C2×C61×#385C211yesmaximal, characteristic
5C2×C61×#381C211yesmaximal, characteristic
6C61×#1446C211yesmaximal, characteristic, complemented
7C61×#1444C212yesmaximal, complemented
8C61×#1442C212yesmaximal, complemented
9C61×#1442C211yesmaximal, characteristic, complemented
10C61×#1441C211yesmaximal, characteristic, complemented
11C61×#1440C212yesmaximal
12C23×Q8×C61C2211yescharacteristic
13C24×C4×C61C2211yescharacteristic
14C2×C22⋊Q8×C61—24no—
15C2×C22⋊Q8×C61—28no—
16C22×C4⋊C4×C61C2211yescharacteristic
17C22×C4⋊C4×C61C2211yescharacteristic
18C22×C4⋊C4×C61C2212yes—
19C22×C4⋊C4×C61C2212yes—
20C22×C4⋊C4×C61C2211yescharacteristic
21C22×C22⋊C4×C61C2211yescharacteristic
22C22×C22⋊C4×C61C2211yescharacteristic
23C22×C22⋊C4×C61C2212yes—
24C22×C22⋊C4×C61C2212yes—
25C61×#397—28no—
26C61×#395—24no—
27C61×#385—24no—
28C61×#381—24no—
29C2×#95×C61C2211yescharacteristic
30C2×#95×C61C2212yes—
31C2×#95×C61C2211yescharacteristic
32C2×#95×C61C2211yescharacteristic
33C2×#95×C61C2212yes—
34C2×#95×C61C2212yes—
35C2×#95×C61C2212yes—
36C2×#95×C61C2212yes—
37C2×#95×C61C2212yes—
38C2×#95×C61C2212yes—
39C2×#95×C61C2212yes—
40C2×#95×C61C2211yescharacteristic
41C25×C61C2311yescharacteristic
42C22×Q8×C61—24no—
43C22×Q8×C61—22no—
44C22×Q8×C61—22no—
45C22×Q8×C61—22no—
46C22×Q8×C61—42no—
47C23×C4×C61—24no—
48C23×C4×C61—22no—
49C23×C4×C61—22no—
50C23×C4×C61—42no—
51C23×C4×C61D414yes—
52C23×C4×C61C2311yescharacteristic
53C23×C4×C61C2312yes—
54C23×C4×C61C2311yescharacteristic
55C23×C4×C61C2311yescharacteristic
56C23×C4×C61C2312yes—
57C23×C4×C61C2312yes—
58C23×C4×C61C2312yes—
59C23×C4×C61C2311yescharacteristic
60C23×C4×C61C2311yescharacteristic
61C23×C4×C61C2311yescharacteristic
62C22⋊Q8×C61—232no—
63C2×C4⋊C4×C61—24no—
64C2×C4⋊C4×C61—22no—
65C2×C4⋊C4×C61—24no—
66C2×C4⋊C4×C61—24no—
67C2×C4⋊C4×C61—24no—
68C2×C4⋊C4×C61—22no—
69C2×C4⋊C4×C61—22no—
70C2×C4⋊C4×C61—24no—
71C2×C4⋊C4×C61—22no—
72C2×C4⋊C4×C61—24no—
73C2×C4⋊C4×C61—22no—
74C2×C4⋊C4×C61—42no—
75C2×C4⋊C4×C61—42no—
76C2×C22⋊C4×C61—22no—
77C2×C22⋊C4×C61—24no—
78C2×C22⋊C4×C61—24no—
79C2×C22⋊C4×C61—22no—
80C2×C22⋊C4×C61—22no—
81C2×C22⋊C4×C61—22no—
82C2×C22⋊C4×C61—24no—
83C2×C22⋊C4×C61—24no—
84C2×C22⋊C4×C61—24no—
85C2×C22⋊C4×C61—42no—
86C2×C22⋊C4×C61D418yes—
87#95×C61—24no—
88#95×C61—22no—
89#95×C61—22no—
90#95×C61—22no—
91#95×C61—24no—
92#95×C61—24no—
93#95×C61—24no—
94#95×C61—24no—
95#95×C61—24no—
96#95×C61—24no—
97#95×C61—42no—
98#95×C61D414yes—
99C24×C61—21no—
100C24×C61—21no—
101C24×C61—21no—
102C24×C61—21no—
103C24×C61—22no—
104C24×C61—22no—
105C24×C61—21no—
106C24×C61—21no—
107C24×C61—22no—
108C24×C61C2×D412yes—
109C24×C61C2×D414yes—
110C24×C61C2411yescharacteristic
111C2×Q8×C61—28no—
112C2×Q8×C61—48no—
113C2×Q8×C61—48no—
114C2×Q8×C61—44no—
115C2×Q8×C61—44no—
116C22×C4×C61—22no—
117C22×C4×C61—22no—
118C22×C4×C61—28no—
119C22×C4×C61—21no—
120C22×C4×C61—21no—
121C22×C4×C61—21no—
122C22×C4×C61—21no—
123C22×C4×C61—22no—
124C22×C4×C61—22no—
125C22×C4×C61—22no—
126C22×C4×C61—22no—
127C22×C4×C61—22no—
128C22×C4×C61—22no—
129C22×C4×C61—22no—
130C22×C4×C61—22no—
131C22×C4×C61—22no—
132C22×C4×C61—22no—
133C22×C4×C61—21no—
134C22×C4×C61—21no—
135C22×C4×C61—21no—
136C22×C4×C61—21no—
137C22×C4×C61—22no—
138C22×C4×C61—22no—
139C22×C4×C61—22no—
140C22×C4×C61—22no—
141C22×C4×C61—22no—
142C22×C4×C61—22no—
143C22×C4×C61—22no—
144C22×C4×C61—22no—
145C22×C4×C61—22no—
146C22×C4×C61—22no—
147C22×C4×C61—22no—
148C22×C4×C61—22no—
149C22×C4×C61—21no—
150C22×C4×C61—21no—
151C22×C4×C61—28no—
152C22×C4×C61—21no—
153C22×C4×C61—22no—
154C22×C4×C61—22no—
155C22×C4×C61—22no—
156C22×C4×C61—22no—
157C22×C4×C61—21no—
158C22×C4×C61—21no—
159C22×C4×C61—22no—
160C22×C4×C61—21no—
161C22×C4×C61—22no—
162C22×C4×C61—22no—
163C22×C4×C61—22no—
164C22×C4×C61—21no—
165C22×C4×C61—21no—
166C22×C4×C61—22no—
167C22×C4×C61—22no—
168C22×C4×C61—22no—
169C22×C4×C61—44no—
170C22×C4×C61—48no—
171C22×C4×C61—48no—
172C22×C4×C61C2×D414yes—
173C22×C4×C61C2×D414yes—
174C22×C4×C61C2×D414yes—
175C22×C4×C61C2×D412yes—
176C22×C4×C61C2×D412yes—
177C22×C4×C61C2×D412yes—
178C22×C4×C61#4112yes—
179C22×C4×C61#4112yes—
180C22×C4×C61#4112yes—
181C4⋊C4×C61—28no—
182C4⋊C4×C61—216no—
183C4⋊C4×C61—48no—
184C4⋊C4×C61—44no—
185C4⋊C4×C61—44no—
186C22⋊C4×C61—28no—
187C22⋊C4×C61—216no—
188C22⋊C4×C61—48no—
189C22⋊C4×C61—44no—
190C23×C61—22no—
191C23×C61—22no—
192C23×C61—22no—
193C23×C61—22no—
194C23×C61—22no—
195C23×C61—24no—
196C23×C61—24no—
197C23×C61—22no—
198C23×C61—24no—
199C23×C61—24no—
200C23×C61—24no—
201C23×C61—24no—
202C23×C61—42no—
203C23×C61—42no—
204C23×C61—42no—
205C23×C61—42no—
206C23×C61—41no—
207C23×C61—41no—
208C23×C61—41no—
209C23×C61—41no—
210C23×C61—42no—
211C23×C61—42no—
212C23×C61#12014yes—
213C23×C61C22×D411yescharacteristic
214C23×C61C22×D412yes—
215C23×C61C22×D411yescharacteristic
216C23×C61C2×#4111yescharacteristic
217C23×C61C2×#4111yescharacteristic
218C23×C61C2×#4111yescharacteristic
219C23×C61H(5,𝔽2)12yes—
220C23×C612−1+412yes—
221C23×C612−1+411yescharacteristic
222C23×C612−1+411yescharacteristic
223C23×C612−1+412yes—
224Q8×C61—416no—
225C2×C4×C61—22no—
226C2×C4×C61—22no—
227C2×C4×C61—24no—
228C2×C4×C61—24no—
229C2×C4×C61—24no—
230C2×C4×C61—24no—
231C2×C4×C61—22no—
232C2×C4×C61—22no—
233C2×C4×C61—22no—
234C2×C4×C61—22no—
235C2×C4×C61—22no—
236C2×C4×C61—24no—
237C2×C4×C61—24no—
238C2×C4×C61—24no—
239C2×C4×C61—24no—
240C2×C4×C61—24no—
241C2×C4×C61—24no—
242C2×C4×C61—24no—
243C2×C4×C61—24no—
244C2×C4×C61—22no—
245C2×C4×C61—22no—
246C2×C4×C61—416no—
247C2×C4×C61—41no—
248C2×C4×C61—42no—
249C2×C4×C61—42no—
250C2×C4×C61—41no—
251C2×C4×C61—42no—
252C2×C4×C61—41no—
253C2×C4×C61—42no—
254C2×C4×C61—41no—
255C2×C4×C61—42no—
256C2×C4×C61—42no—
257C2×C4×C61—42no—
258C2×C4×C61—42no—
259C2×C4×C61—42no—
260C2×C4×C61—42no—
261C2×C4×C61—42no—
262C2×C4×C61—42no—
263C2×C4×C61—42no—
264C2×C4×C61—41no—
265C2×C4×C61—42no—
266C2×C4×C61—41no—
267C2×C4×C61—42no—
268C2×C4×C61—41no—
269C2×C4×C61—41no—
270C2×C4×C61—41no—
271C2×C4×C61—41no—
272C2×C4×C61—41no—
273C2×C4×C61—41no—
274C2×C4×C61—42no—
275C2×C4×C61—42no—
276C2×C4×C61—42no—
277C2×C4×C61—42no—
278C2×C4×C61—42no—
279C2×C4×C61—42no—
280C2×C4×C61—42no—
281C2×C4×C61—42no—
282C2×C4×C61—42no—
283C2×C4×C61—42no—
284C2×C4×C61—42no—
285C2×C4×C61#12114yes—
286#16262C6111yesmaximal, characteristic, direct product factor, Sylow
287C22×C61—24no—
288C22×C61—24no—
289C22×C61—24no—
290C22×C61—42no—
291C22×C61—42no—
292C22×C61—42no—
293C22×C61—42no—
294C22×C61—44no—
295C22×C61—44no—
296C22×C61—44no—
297C22×C61—44no—
298C22×C61C2×#12011yescharacteristic
299C22×C61C2×#12111yescharacteristic
300C22×C61#52511yescharacteristic
301C22×C61#53411yescharacteristic
302C22×C61#53611yescharacteristic
303C22×C61#53611yescharacteristic
304C22×C61#53611yescharacteristic
305C22×C61#53612yes—
306C22×C61#53612yes—
307C22×C61#53612yes—
308C22×C61#53912yes—
309C22×C61#54112yes—
310C22×C61#54212yes—
311C22×C61D4212yes—
312C22×C61#54612yes—
313C22×C61#54712yes—
314C22×C61#54712yes—
315C22×C61#54711yescharacteristic
316C22×C61#54811yescharacteristic
317C22×C61#55211yescharacteristic
318C22×C61#55611yescharacteristic
319C22×C61#56312yes—
320C22×C61#56312yes—
321C4×C61—24no—
322C4×C61—42no—
323C4×C61—44no—
324C4×C61—42no—
325C4×C61—44no—
326C4×C61—42no—
327C4×C61—44no—
328C4×C61—81no—
329C4×C61—81no—
330C4×C61—82no—
331C22×C22⋊Q8C2×C6111yescharacteristic
332C2×#397C2×C6112yes—
333C2×#395C2×C6111yescharacteristic, complemented
334C2×#385C2×C6111yescharacteristic
335C2×#381C2×C6111yescharacteristic
336#1446C2×C6111yescharacteristic, complemented
337#1444C2×C6112yescomplemented
338#1442C2×C6111yescharacteristic, complemented
339#1442C2×C6112yescomplemented
340#1441C2×C6111yescharacteristic, complemented
341#1440C2×C6112yes—
342C2×C61—44no—
343C2×C61#240611yescharacteristic
344C2×C61#241011yescharacteristic
345C2×C61#241511yescharacteristic
346C2×C61#261411yescharacteristic
347C2×C61#262111yescharacteristic
348C2×C61#263811yescharacteristic
349C2×C61#267412yes—
350C2×C61#268012yes—
351C2×C61#268912yes—
352C2×C61#269812yes—
353C2×C61#281711yescharacteristic
354C23×Q8C22×C6111yescharacteristic
355C24×C4C22×C6111yescharacteristic
356C2×C22⋊Q8—24no—
357C2×C22⋊Q8—28no—
358C22×C4⋊C4C22×C6111yescharacteristic
359C22×C4⋊C4C22×C6111yescharacteristic
360C22×C4⋊C4C22×C6112yes—
361C22×C4⋊C4C22×C6112yes—
362C22×C4⋊C4C22×C6111yescharacteristic
363C22×C22⋊C4C22×C6111yescharacteristic
364C22×C22⋊C4C22×C6111yescharacteristic
365C22×C22⋊C4C22×C6112yes—
366C22×C22⋊C4C22×C6112yes—
367#397—28no—
368#395—24no—
369#385—24no—
370#381—24no—
371C2×#95C22×C6112yes—
372C2×#95C22×C6112yes—
373C2×#95C22×C6112yes—
374C2×#95C22×C6112yes—
375C2×#95C22×C6112yes—
376C2×#95C22×C6112yes—
377C2×#95C22×C6111yescharacteristic
378C2×#95C22×C6111yescharacteristic
379C2×#95C22×C6112yes—
380C2×#95C22×C6111yescharacteristic
381C2×#95C22×C6112yes—
382C2×#95C22×C6111yescharacteristic
383C61#1626211yescharacteristic, direct product factor, Sylow
384C25C23×C6111yescharacteristic
385C22×Q8—24no—
386C22×Q8—22no—
387C22×Q8—22no—
388C22×Q8—22no—
389C22×Q8—42no—
390C23×C4—24no—
391C23×C4—22no—
392C23×C4—22no—
393C23×C4—42no—
394C23×C4D4×C6114yes—
395C23×C4C23×C6111yescharacteristic
396C23×C4C23×C6111yescharacteristic
397C23×C4C23×C6112yes—
398C23×C4C23×C6112yes—
399C23×C4C23×C6112yes—
400C23×C4C23×C6112yes—
401C23×C4C23×C6111yescharacteristic
402C23×C4C23×C6111yescharacteristic
403C23×C4C23×C6111yescharacteristic
404C23×C4C23×C6111yescharacteristic
405C22⋊Q8—232no—
406C2×C4⋊C4—24no—
407C2×C4⋊C4—22no—
408C2×C4⋊C4—24no—
409C2×C4⋊C4—24no—
410C2×C4⋊C4—24no—
411C2×C4⋊C4—22no—
412C2×C4⋊C4—22no—
413C2×C4⋊C4—24no—
414C2×C4⋊C4—22no—
415C2×C4⋊C4—24no—
416C2×C4⋊C4—22no—
417C2×C4⋊C4—42no—
418C2×C4⋊C4—42no—
419C2×C22⋊C4—24no—
420C2×C22⋊C4—24no—
421C2×C22⋊C4—22no—
422C2×C22⋊C4—22no—
423C2×C22⋊C4—22no—
424C2×C22⋊C4—22no—
425C2×C22⋊C4—24no—
426C2×C22⋊C4—24no—
427C2×C22⋊C4—24no—
428C2×C22⋊C4—42no—
429C2×C22⋊C4D4×C6118yes—
430#95—24no—
431#95—22no—
432#95—22no—
433#95—22no—
434#95—24no—
435#95—24no—
436#95—24no—
437#95—24no—
438#95—24no—
439#95—24no—
440#95—42no—
441#95D4×C6114yes—
442C24—21no—
443C24—21no—
444C24—21no—
445C24—21no—
446C24—22no—
447C24—22no—
448C24—21no—
449C24—21no—
450C24—22no—
451C24C2×D4×C6112yes—
452C24C2×D4×C6114yes—
453C24C24×C6111yescharacteristic
454C2×Q8—28no—
455C2×Q8—48no—
456C2×Q8—48no—
457C2×Q8—44no—
458C2×Q8—44no—
459C22×C4—22no—
460C22×C4—22no—
461C22×C4—28no—
462C22×C4—21no—
463C22×C4—21no—
464C22×C4—22no—
465C22×C4—21no—
466C22×C4—21no—
467C22×C4—22no—
468C22×C4—22no—
469C22×C4—22no—
470C22×C4—22no—
471C22×C4—22no—
472C22×C4—22no—
473C22×C4—22no—
474C22×C4—22no—
475C22×C4—22no—
476C22×C4—21no—
477C22×C4—21no—
478C22×C4—21no—
479C22×C4—21no—
480C22×C4—22no—
481C22×C4—22no—
482C22×C4—22no—
483C22×C4—22no—
484C22×C4—22no—
485C22×C4—22no—
486C22×C4—22no—
487C22×C4—22no—
488C22×C4—22no—
489C22×C4—22no—
490C22×C4—22no—
491C22×C4—22no—
492C22×C4—21no—
493C22×C4—21no—
494C22×C4—28no—
495C22×C4—21no—
496C22×C4—22no—
497C22×C4—22no—
498C22×C4—22no—
499C22×C4—22no—
500C22×C4—21no—
501C22×C4—21no—
502C22×C4—22no—
503C22×C4—21no—
504C22×C4—22no—
505C22×C4—22no—
506C22×C4—22no—
507C22×C4—21no—
508C22×C4—21no—
509C22×C4—22no—
510C22×C4—22no—
511C22×C4—22no—
512C22×C4—44no—
513C22×C4—48no—
514C22×C4—48no—
515C22×C4C2×D4×C6114yes—
516C22×C4C2×D4×C6114yes—
517C22×C4C2×D4×C6114yes—
518C22×C4C2×D4×C6112yes—
519C22×C4C2×D4×C6112yes—
520C22×C4C2×D4×C6112yes—
521C22×C4#41×C6112yes—
522C22×C4#41×C6112yes—
523C22×C4#41×C6112yes—
524C4⋊C4—28no—
525C4⋊C4—216no—
526C4⋊C4—48no—
527C4⋊C4—44no—
528C4⋊C4—44no—
529C22⋊C4—28no—
530C22⋊C4—216no—
531C22⋊C4—48no—
532C22⋊C4—44no—
533C23—22no—
534C23—22no—
535C23—22no—
536C23—24no—
537C23—24no—
538C23—22no—
539C23—24no—
540C23—24no—
541C23—24no—
542C23—24no—
543C23—22no—
544C23—22no—
545C23—42no—
546C23—42no—
547C23—42no—
548C23—42no—
549C23—41no—
550C23—41no—
551C23—41no—
552C23—41no—
553C23—42no—
554C23—42no—
555C23#120×C6114yes—
556C23C22×D4×C6111yescharacteristic
557C23C22×D4×C6111yescharacteristic
558C23C22×D4×C6112yes—
559C23C2×#41×C6111yescharacteristic
560C23C2×#41×C6111yescharacteristic
561C23C2×#41×C6111yescharacteristic
562C23H(5,𝔽2)×C6112yes—
563C232−1+4×C6112yes—
564C232−1+4×C6111yescharacteristic
565C232−1+4×C6111yescharacteristic
566C232−1+4×C6112yes—
567Q8—416no—
568C2×C4—22no—
569C2×C4—24no—
570C2×C4—24no—
571C2×C4—22no—
572C2×C4—22no—
573C2×C4—24no—
574C2×C4—24no—
575C2×C4—24no—
576C2×C4—24no—
577C2×C4—24no—
578C2×C4—24no—
579C2×C4—24no—
580C2×C4—24no—
581C2×C4—22no—
582C2×C4—22no—
583C2×C4—24no—
584C2×C4—24no—
585C2×C4—22no—
586C2×C4—22no—
587C2×C4—22no—
588C2×C4—22no—
589C2×C4—416no—
590C2×C4—41no—
591C2×C4—42no—
592C2×C4—41no—
593C2×C4—42no—
594C2×C4—41no—
595C2×C4—42no—
596C2×C4—42no—
597C2×C4—42no—
598C2×C4—42no—
599C2×C4—42no—
600C2×C4—42no—
601C2×C4—42no—
602C2×C4—42no—
603C2×C4—42no—
604C2×C4—41no—
605C2×C4—42no—
606C2×C4—41no—
607C2×C4—42no—
608C2×C4—41no—
609C2×C4—42no—
610C2×C4—42no—
611C2×C4—41no—
612C2×C4—41no—
613C2×C4—41no—
614C2×C4—42no—
615C2×C4—42no—
616C2×C4—42no—
617C2×C4—42no—
618C2×C4—42no—
619C2×C4—42no—
620C2×C4—42no—
621C2×C4—42no—
622C2×C4—42no—
623C2×C4—42no—
624C2×C4—42no—
625C2×C4—41no—
626C2×C4—41no—
627C2×C4—41no—
628C2×C4#121×C6114yes—
629C22—24no—
630C22—24no—
631C22—24no—
632C22—42no—
633C22—42no—
634C22—42no—
635C22—42no—
636C22—44no—
637C22—44no—
638C22—44no—
639C22—44no—
640C22C2×#120×C6111yescharacteristic
641C22C2×#121×C6111yescharacteristic
642C22C61×#52511yescharacteristic
643C22C61×#53411yescharacteristic
644C22C61×#53611yescharacteristic
645C22C61×#53611yescharacteristic
646C22C61×#53611yescharacteristic
647C22C61×#53612yes—
648C22C61×#53612yes—
649C22C61×#53612yes—
650C22C61×#53912yes—
651C22C61×#54112yes—
652C22C61×#54212yes—
653C22D42×C6112yes—
654C22C61×#54612yes—
655C22C61×#54712yes—
656C22C61×#54712yes—
657C22C61×#54711yescharacteristic
658C22C61×#54811yescharacteristic
659C22C61×#55211yescharacteristic
660C22C61×#55611yescharacteristic
661C22C61×#56312yes—
662C22C61×#56312yes—
663C4—24no—
664C4—42no—
665C4—44no—
666C4—42no—
667C4—44no—
668C4—42no—
669C4—44no—
670C4—81no—
671C4—81no—
672C4—82no—
673C2—44no—
674C2C61×#240611yescharacteristic
675C2C61×#241011yescharacteristic
676C2C61×#241511yescharacteristic
677C2C61×#261411yescharacteristic
678C2C61×#262111yescharacteristic
679C2C61×#263811yescharacteristic
680C2C61×#267412yes—
681C2C61×#268012yes—
682C2C61×#268912yes—
683C2C61×#269812yes—
684C2C61×#281711yescharacteristic
subgroupG/H
center, socleC24×C61C24
commutator, Frattini, cosocleC24C24×C61
prime radicalC25×C61C23
LCSG ▷ C24 ▷ C1
UCSC1 ◁ C24×C61 ◁ G

Complements

Splittings G = N ⋊ H with N normal; H ≅ G/N.

NH ≅ G/Ntype
3. C2×C61×#395C2semidirect
6. C61×#1446C2semidirect
7. C61×#1444C2semidirect
8. C61×#1442C2semidirect
9. C61×#1442C2semidirect
10. C61×#1441C2semidirect
286. #16262C61direct (N × H)
333. C2×#395C2×C61semidirect
336. #1446C2×C61semidirect
337. #1444C2×C61semidirect
338. #1442C2×C61semidirect
339. #1442C2×C61semidirect
340. #1441C2×C61semidirect
383. C61#16262direct (N × H)

Maximal subgroups

By isomorphism type — maximal subgroups of the same type appear once, whether or not they are normal.

subgroupindex
C22×C22⋊Q8×C612
C2×C61×#3972
C2×C61×#3952
C2×C61×#3852
C2×C61×#3812
C61×#14462
C61×#14442
C61×#14422
C61×#14412
C61×#14402
#1626261