A024176 a(n) = (n+2)!(1/3 - 1/4 + ... + c/(n+2)), where c=(-1)^(n+1).

2, 2, 34, 84, 1308, 5424, 89136, 528480, 9442080, 73388160, 1433047680, 13835646720, 294712992000, 3407733504000, 78854259456000, 1063689242112000, 26612469305856000, 410604285708288000, 11055592008050688000, 192132082005405696000, 5543038613901938688000

Offset

1,1

Links

Andrew Howroyd, Table of n, a(n) for n = 1..100

Formula

a(n) = 2*A024188(n).

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

Mathematica

Table[(n+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)); \\ Michel Marcus, Mar 21 2013

Crossrefs

Cf. A024188.

Sequence in context: A018976 A074127 A297795 * A349033 A334470 A286375

Adjacent sequences: A024173 A024174 A024175 * A024177 A024178 A024179

Keyword

nonn

Author

Clark Kimberling

Extensions

Terms a(13) and beyond from Andrew Howroyd, Jan 01 2020

Status

approved