A191424 E.g.f. exp(exp(1/2*x^2+1/6*x^3)-1).

1, 0, 1, 1, 6, 20, 95, 525, 2975, 20300, 143640, 1131900, 9548385, 86096010, 831475645, 8488104625, 91828436700, 1045926081200, 12517301471675, 157022728337475, 2058625791347125, 28160968442356750, 401055626173702500, 5936491984459286250

Offset

0,5

Links

Table of n, a(n) for n=0..23.

Formula

a(n)=n!*sum(m=1..n, sum(k=m..n, (stirling2(k,m)*binomial(k,n-2*k)*3^(2*k-n)*2^(-k))/k!)), n>0, a(0)=1.

Prog

(Maxima)
a(n):=n!*sum(sum((stirling2(k, m)*binomial(k, n-2*k)*3^(2*k-n)*2^(-k))/k!, k, m, n), m, 1, n);

Crossrefs

Sequence in context: A274071 A246036 A151485 * A333048 A200538 A238118

Adjacent sequences: A191421 A191422 A191423 * A191425 A191426 A191427

Keyword

nonn

Author

Vladimir Kruchinin, Jun 05 2011

Status

approved