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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 Table of n, a(n) for n=3..20. 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 Cf. A000142, A001710. Sequence in context: A220868 A296273 A101008 * A009113 A152751 A369953 Adjacent sequences: A070731 A070732 A070733 * A070735 A070736 A070737 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.)