a(n) = (3*n-2)!!! * Sum_{k=0..n} k/(3*k-2)!!!.

A368793

a(n) = (3*n-2)!!! * Sum_{k=0..n} k/(3*k-2)!!!.

Terms

    a(0) =0a(1) =1a(2) =6a(3) =45a(4) =454a(5) =5907a(6) =94518a(7) =1795849a(8) =39508686a(9) =987717159a(10) =27656080462a(11) =857338494333

External references