A228906 - OEIS

%I #3 Sep 07 2013 19:57:28

%S 1,2,7,62,1031,24782,774180,29763855,1359654560,71984907423,

%T 4335406418694,292753300447894,21909289407621069,1800106653483146619,

%U 161097567109713138999,15599377878403186676330,1625083531855929644443019,181238001661004834528467994,21545324993880123460418461719

%N  A diagonal of triangle A228904.

%C  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 ).

%o  (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)}

%o for(n=1, 20, print1(a(n), ", "))

%Y  Cf.  A228904.

%K nonn

%O 1,2

%A _Paul D. Hanna_, Sep 07 2013