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A070734 Order of the subgroup of the symmetric group S_n generated by the cycles (1,2,3) and (1,2,3,...,n). 2
3, 24, 60, 720, 2520, 40320, 181440, 3628800, 19958400, 479001600, 3113510400, 87178291200, 653837184000, 20922789888000, 177843714048000, 6402373705728000, 60822550204416000, 2432902008176640000 (list; graph; refs; listen; history; text; internal format)
OFFSET
3,1
LINKS
FORMULA
For odd n: a(n) = n!/2; for even n: a(n) = n!.
a(n) = (1/4)*(3+(-1)^n)*n! - Benoit Cloitre, May 18 2002
From Amiram Eldar, Jul 06 2022: (Start)
Sum_{n>=3} 1/a(n) = 2*sinh(1) + cosh(1) - 7/2.
Sum_{n>=3} (-1)^(n+1)/a(n) = 2*sinh(1) - cosh(1) - 1/2. (End)
MATHEMATICA
f[n_] := If[ EvenQ[n], n!, n!/2]; Table[ f[n], {n, 3, 24}].
PROG
(PARI) for(n=3, 20, print1((3+(-1)^n)/4*n!, ", "))
CROSSREFS
Sequence in context: A220868 A296273 A101008 * A009113 A152751 A369953
KEYWORD
nonn,easy
AUTHOR
Sharon Sela (sharonsela(AT)hotmail.com), May 14 2002
EXTENSIONS
More terms from Benoit Cloitre, May 18 2002
STATUS
approved

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Last modified July 19 19:50 EDT 2024. Contains 374436 sequences. (Running on oeis4.)