A193469 a(n) = A193467(n)/n for n>=1.

1, 2, 9, 70, 805, 12646, 257179, 6524176, 200811433, 7340612842, 313294235311, 15395868322660, 861109521894637, 54282864059246590, 3824491871326292755, 298974154411140942856, 25767887775430753766353, 2434836258338521063652050

Offset

1,2

Comments

A193467 is defined by the e.g.f.: Sum_{n>=0} x^n * exp(n*(n+1)/2*x).

Links

Table of n, a(n) for n=1..18.

Formula

O.g.f.: x * Sum_{k>=0} k! * x^k / (1 - binomial(k+2,2)*x)^(k+1). - Ilya Gutkovskiy, Jul 16 2019

Prog

(PARI) {a(n)=local(Egf); Egf=sum(m=0, n, x^m*exp(m*(m+1)/2*x+x*O(x^n))); if(n<1, 0, (n-1)!*polcoeff(Egf, n))}

Crossrefs

Cf. A193467.

Sequence in context: A099717 A322772 A177450 * A336606 A121879 A118789

Adjacent sequences: A193466 A193467 A193468 * A193470 A193471 A193472

Keyword

nonn

Author

Paul D. Hanna, Jul 27 2011

Status

approved