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A185757
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Column 2 of triangle A185755.
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4
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6, 120, 2340, 49315, 1142932, 29141994, 814059798, 24779916843, 817506518829, 29081010732059, 1110248649302494, 45298134089851175, 1967550159430960784, 90668183653348456484, 4418855084158930131012, 227122154996245283660487
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OFFSET
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1,1
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COMMENTS
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A185755(n,k) equals the coefficient of x^n*y^k in the n-th iteration of x*(1+xy)/(1-x).
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LINKS
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Table of n, a(n) for n=1..16.
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PROG
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(PARI) {a(n)=local(A=x, G=x*(1+x*y)/(1-x)); for(i=1, n+2, A=subst(G, x, A+O(x^(n+3)))); polcoeff(polcoeff(A, n+2, x), 2, y)}
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CROSSREFS
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Cf. A185755, A185756, A185758, A185759.
Sequence in context: A065888 A246191 A246611 * A075844 A029697 A248045
Adjacent sequences: A185754 A185755 A185756 * A185758 A185759 A185760
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KEYWORD
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nonn
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AUTHOR
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Paul D. Hanna, Feb 03 2011
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STATUS
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approved
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