A384026 a(n) = [x^(2*n)] Product_{k=0..n-1} (1 + k*x)^3.
1, 0, 0, 8, 1188, 240480, 68630824, 26730127872, 13715719388784, 8994742935058880, 7351374493516431744, 7333037983443263351040, 8772990646534399559904256, 12403600039078715891159873280, 20464777911173655904724421045504, 38976211807455406964301439206318080
Offset: 0
Keywords
Programs
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PARI
a(n) = sum(i=0, n, sum(j=0, n-i, abs(stirling(n, i, 1)*stirling(n, j, 1)*stirling(n, n-i-j, 1))));
Formula
a(n) = Sum_{i, j, k>=0 and i+j+k=n} |Stirling1(n,i) * Stirling1(n,j) * Stirling1(n,k)|.