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A191424
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E.g.f. exp(exp(1/2*x^2+1/6*x^3)-1).
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0
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1, 0, 1, 1, 6, 20, 95, 525, 2975, 20300, 143640, 1131900, 9548385, 86096010, 831475645, 8488104625, 91828436700, 1045926081200, 12517301471675, 157022728337475, 2058625791347125, 28160968442356750, 401055626173702500, 5936491984459286250
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OFFSET
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0,5
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LINKS
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FORMULA
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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.
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PROG
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(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);
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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