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A228906
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A diagonal of triangle A228904.
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1
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1, 2, 7, 62, 1031, 24782, 774180, 29763855, 1359654560, 71984907423, 4335406418694, 292753300447894, 21909289407621069, 1800106653483146619, 161097567109713138999, 15599377878403186676330, 1625083531855929644443019, 181238001661004834528467994, 21545324993880123460418461719
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OFFSET
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1,2
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COMMENTS
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Triangle A228904 is defined by g.f.: exp( Sum_{n>=1} x^n/n * Sum_{k=0..n} binomial(n*k, k^2) * y^k ).
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LINKS
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PROG
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(PARI) {a(n)=polcoeff(polcoeff(exp(sum(m=1, n, x^m/m*sum(j=0, m, binomial(m*j, j^2)*y^j))+x*O(x^n)), n, x), n-1, y)}
for(n=1, 20, print1(a(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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