A081050 a(n) = (n! - Stirling1(n+1, 2))*(-1)^n where Stirling1 is A048994.

1, 0, 5, 5, 74, 154, 2484, 8028, 149904, 663696, 14257440, 80627040, 1965444480, 13575738240, 370643938560, 3031488633600, 91657072281600, 867718162483200, 28779361764249600, 309920046408806400, 11185850044938240000

Offset

0,3

Links

Table of n, a(n) for n=0..20.

Formula

a(n) = s(n, 1) - (-1)^(n+1)*s(n, 2), s(n, m) = signed Stirling numbers of first kind.

a(n) = abs(n!*(1 + Sum_{k=1..n}(-1)^n*1/k )).

Prog

(PARI) a(n) = abs(n! - stirling(n+1, 2)) \\ Thomas Scheuerle, Feb 07 2026

Crossrefs

Cf. A081049 (signed version of this sequence).

Cf. A008275, A048994.

Sequence in context: A129358 A318420 A151492 * A081049 A048607 A229767

Adjacent sequences: A081047 A081048 A081049 * A081051 A081052 A081053

Keyword

easy,nonn

Author

Paul Barry, Mar 05 2003

Extensions

Name changed by Thomas Scheuerle, Feb 07 2026

Status

approved