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A diagonal of triangle A228902.
1

%I #3 Sep 07 2013 19:53:53

%S 1,3,45,2905,411500,100545716,37614371968,19977489354808,

%T 14291976911388733,13248449270832615473,15445843697030022753539,

%U 22118947642938636936616739,38166279965353127309979185861,78098472647949324804924786089941,186993874842690500015923551395259661

%N A diagonal of triangle A228902.

%C Triangle A228902 is defined by g.f.: exp( Sum_{n>=1} x^n/n * Sum_{k=0..n} binomial(n^2, k^2) * y^k ).

%o (PARI) {a(n)=polcoeff(polcoeff(exp(sum(m=1, n, x^m/m*sum(j=0, m, binomial(m^2, j^2)*y^j))+x*O(x^n)), n, x), n-1, y)}

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

%Y Cf. A228902.

%K nonn

%O 1,2

%A _Paul D. Hanna_, Sep 07 2013