a(n) = n!^3 * Sum_{k=0..n} Stirling2(2*k,k) * Stirling2(2*n-2*k,n-k) / binomial(n,k)^3.

A384492

a(n) = n!^3 * Sum_{k=0..n} Stirling2(2*k,k) * Stirling2(2*n-2*k,n-k) / binomial(n,k)^3.

Terms

    a(0) =1a(1) =2a(2) =113a(3) =38992a(4) =47071264a(5) =147015606528

External references