a(n) = Sum_{k=1..n} k^k.

Terms

a(0) =0a(1) =1a(2) =5a(3) =32a(4) =288a(5) =3413a(6) =50069a(7) =873612a(8) =17650828a(9) =405071317a(10) =10405071317a(11) =295716741928