a(n) = Sum_{k=0..n} C(n,k)^n.A167010a(n) = Sum_{k=0..n} C(n,k)^n.Terms a(0) =1a(1) =2a(2) =6a(3) =56a(4) =1810a(5) =206252a(6) =86874564a(7) =132282417920External referencesoeis: A167010