a(n) = Sum_{k=0..n} (k!)^2 * binomial(k+3,3) * Stirling2(n+1,k+1)^2.

A382678

a(n) = Sum_{k=0..n} (k!)^2 * binomial(k+3,3) * Stirling2(n+1,k+1)^2.

Terms

    a(0) =1a(1) =5a(2) =77a(3) =2357a(4) =118061a(5) =8712245a(6) =886143917a(7) =118592620277

External references