A024188 a(n) = ((n+2)!/2)(1/3 - 1/4 + ... + c/(n+2)), where c = (-1)^(n+1).

1, 1, 17, 42, 654, 2712, 44568, 264240, 4721040, 36694080, 716523840, 6917823360, 147356496000, 1703866752000, 39427129728000, 531844621056000, 13306234652928000, 205302142854144000, 5527796004025344000, 96066041002702848000, 2771519306950969344000

Offset

1,3

Links

Andrew Howroyd, Table of n, a(n) for n = 1..200

Formula

a(n) = A024176(n)/2.

a(n) ~ sqrt(Pi/2) * (log(2) - 1/2) * n^(n + 5/2) / exp(n). - Vaclav Kotesovec, Jan 02 2020

Mathematica

Table[(n+2)!/2 * Sum[(-1)^(k+1)/k, {k, 3, n+2}], {n, 1, 25}] (* Vaclav Kotesovec, Jan 02 2020 *)

Prog

(PARI) a(n) = (n+2)!*sum(x=1, n, (-1)^(x+1)/(x+2))/2 \\Michel Marcus, Mar 21 2013

Crossrefs

Cf. A024176.

Sequence in context: A253605 A044094 A044475 * A196209 A196476 A086006

Adjacent sequences: A024185 A024186 A024187 * A024189 A024190 A024191

Keyword

nonn

Author

Clark Kimberling

Extensions

Terms a(16) and beyond from Andrew Howroyd, Jan 01 2020

Status

approved