A228906 - OEIS

A228906

A diagonal of triangle A228904.

1, 2, 7, 62, 1031, 24782, 774180, 29763855, 1359654560, 71984907423, 4335406418694, 292753300447894, 21909289407621069, 1800106653483146619, 161097567109713138999, 15599377878403186676330, 1625083531855929644443019, 181238001661004834528467994, 21545324993880123460418461719

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OFFSET

1,2

COMMENTS

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 ).

LINKS

Table of n, a(n) for n=1..19.

PROG

(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), ", "))

CROSSREFS

Cf. A228904.