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A274634
a(n) = n!*A003436(n).
3
0, 2, 24, 744, 35160, 2394720, 222712560, 27154350720, 4205374225920, 806700010233600, 187793061031699200, 52162131258836121600, 17043501717850146739200, 6471785359791584459827200, 2826261760629911644744704000, 1406604814631643298586923008000
OFFSET
1,2
LINKS
FORMULA
a(n) ~ 2*sqrt(Pi*n)*2^n*n^(2*n)/exp(2*n+1). - Ilya Gutkovskiy, Aug 18 2016
MATHEMATICA
a[n_]:= n! (2 n - 1)!! Hypergeometric1F1[-n, 1 - 2 n, - 2]; a[1] = 0; Table[a[n], {n, 1, 20}] (* Vincenzo Librandi, Aug 18 2016 *)
CROSSREFS
Cf. A003436.
Sequence in context: A177771 A009396 A338188 * A292694 A012128 A099704
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jul 08 2016
STATUS
approved