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A191424
E.g.f. exp(exp(1/2*x^2+1/6*x^3)-1).
0
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
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
KEYWORD
nonn
AUTHOR
Vladimir Kruchinin, Jun 05 2011
STATUS
approved