a(n) = Sum_{k=0..n} (k!)^2 * binomial(k+2,2) * Stirling2(n+1,k+1)^2.

A382676

a(n) = Sum_{k=0..n} (k!)^2 * binomial(k+2,2) * Stirling2(n+1,k+1)^2.

Terms

    a(0) =1a(1) =4a(2) =52a(3) =1372a(4) =60316a(5) =3964684a(6) =363503932a(7) =44280657292

External references