Sum(binomial(n,k)*n^k*k^n,k=1..n).A072035Sum(binomial(n,k)*n^k*k^n,k=1..n).Terms a(0) =1a(1) =20a(2) =954a(3) =87824a(4) =13277400a(5) =2988592452a(6) =937739606608External referencesoeis: A072035