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A135746
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E.g.f.: A(x) = Sum_{n>=0} exp(n^2*x) * x^n/n!.
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5
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1, 1, 3, 16, 137, 1536, 22417, 407884, 8920641, 230576320, 6928080641, 238375169484, 9288784476193, 406150114297552, 19761959813464065, 1062437048084297596, 62727815353861478273, 4045278841893314992896
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OFFSET
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0,3
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LINKS
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Table of n, a(n) for n=0..17.
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FORMULA
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a(n) = Sum_{k=0..n} C(n,k)*(k^2)^(n-k).
O.g.f.: Sum_{n>=0} x^n/(1 - n^2*x)^(n+1). [From Paul D. Hanna, Aug 08 2009]
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EXAMPLE
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E.g.f.: A(x) = 1 + x + 3*x^2/2! + 16*x^3/3! + 137*x^4/4! + 1536*x^5/5! +...
where A(x) = 1 + exp(x)*x + exp(4*x)*x^2/2! + exp(9*x)*x^3/3! + exp(16*x)*x^4/4! + exp(25*x)*x^5/5! +...
O.g.f.: F(x) = 1 + x + 3*x^2 + 16*x^3 + 137*x^4 + 1536*x^5 + 22417*x^6 +...
where F(x) = 1 + x/(1-x)^2 + x^2/(1-4*x)^3 + x^3/(1-9*x)^4 + x^4/(1-16*x)^5 + x^5/(1-25*x)^6 +...
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PROG
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(PARI) {a(n)=sum(k=0, n, binomial(n, k)*(k^2)^(n-k))}
(PARI) {a(n)=n!*polcoeff(sum(k=0, n, exp(k^2*x +x*O(x^n))*x^k/k!), n)}
(PARI) {a(n)=polcoeff(sum(k=0, n, x^k/(1-k^2*x +x*O(x^n))^(k+1)), n)} [From Paul D. Hanna, Aug 08 2009]
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CROSSREFS
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Cf. variants: A135742, A135743, A135744, A135745, A135747.
Sequence in context: A119392 A129043 A182951 * A006057 A002719 A020554
Adjacent sequences: A135743 A135744 A135745 * A135747 A135748 A135749
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KEYWORD
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nonn
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AUTHOR
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Paul D. Hanna, Nov 27 2007
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STATUS
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approved
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