A368793 a(n) = (3*n-2)!!! * Sum_{k=0..n} k/(3*k-2)!!!.
0, 1, 6, 45, 454, 5907, 94518, 1795849, 39508686, 987717159, 27656080462, 857338494333, 29149508807334, 1078531825871371, 43141273034854854, 1855074740498758737, 85333438062942901918, 4181338465084202193999, 217429600184378514087966
Offset: 0
Keywords
Programs
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PARI
a007559(n) = prod(k=1, n, 3*k-2); a(n) = a007559(n)*sum(k=0, n, k/a007559(k));
Formula
a(0) = 0; a(n) = (3*n-2)*a(n-1) + n.