A374676 a(n) = Sum_{k=0..n} binomial(n+k-1,n) * binomial(n+k,n)^2.
1, 4, 117, 4416, 191025, 8959098, 443175257, 22764880288, 1202693106969, 64935435950760, 3567189106107044, 198746486074429164, 11203798260525398593, 637866038409406067394, 36624374381748740836905, 2118319467225018572438976, 123307986154526506959597225
Offset: 0
Keywords
Programs
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PARI
a(n) = sum(k=0, n, binomial(n+k-1, n)*binomial(n+k, n)^2);
Formula
a(n) = Sum_{k=0..n} (k/(n+k)) * binomial(n+k,k)^3 for n > 0.