A371234 E.g.f. satisfies A(x) = 1 - x^2*A(x)^4*log(1 - x*A(x)^2).

1, 0, 0, 6, 12, 40, 4500, 36288, 302400, 21280320, 372808800, 5690583360, 328776433920, 9448800042240, 224460513268992, 12193757153424000, 487602908139110400, 16244434378146723840, 899553800205694310400, 45212291317983663820800

Offset: 0

Author

Seiichi Manyama, Mar 15 2024

Keywords

• nonn

Crossrefs

Cf. A371233, A371235.

Cf. A371234.

Programs

PARI

a(n) = n!*(2*n)!*sum(k=0, n\3, abs(stirling(n-2*k, k, 1))/((n-2*k)!*(2*n-k+1)!));

Formula

a(n) = n! * (2*n)! * Sum_{k=0..floor(n/3)} |Stirling1(n-2*k,k)|/( (n-2*k)! * (2*n-k+1)! ).