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A185759
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A diagonal of triangle A185755.
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4
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9, 154, 2340, 38325, 704102, 14570976, 337738758, 8697532008, 246819113442, 7660379273261, 258275171344333, 9403520522325228, 367786323703199388, 15381080863799688012, 684987041358431417024, 32366520461834117146792
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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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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), n-1, y)}
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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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