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A069660 Order of the subgroup of the symmetric group S_n generated by the cycles (1,3) and (1,2,3,...,n). 0
6, 8, 120, 72, 5040, 1152, 362880, 28800, 39916800, 1036800, 6227020800, 50803200, 1307674368000, 3251404800, 355687428096000, 263363788800, 121645100408832000, 26336378880000, 51090942171709440000 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,1

LINKS

Table of n, a(n) for n=3..21.

FORMULA

If n is odd a(n) = n!, if n is even a(n) = 2 * ((n/2)!)^2 = 2 * n! / A000984(n/2) = 2 * A001044(n/2).

CROSSREFS

Cf. A000984, A070734, A000142, A009445, A001044.

Sequence in context: A161801 A211041 A236754 * A119001 A324987 A013239

Adjacent sequences:  A069657 A069658 A069659 * A069661 A069662 A069663

KEYWORD

nonn,easy

AUTHOR

Sharon Sela (sharonsela(AT)hotmail.com), May 16 2002

EXTENSIONS

More terms from Benoit Cloitre, May 20 2002

STATUS

approved

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Last modified August 7 22:44 EDT 2020. Contains 336279 sequences. (Running on oeis4.)