a(n) = Sum_{d|n} d^(n/d-1) * (n/d)^(d-1).

Terms

a(0) =1a(1) =2a(2) =2a(3) =6a(4) =2a(5) =26a(6) =2a(7) =66a(8) =83a(9) =162a(10) =2a(11) =1250a(12) =2a(13) =898a(14) =4052a(15) =6146a(16) =2a(17) =22106a(18) =2a(19) =74242a(20) =71444a(21) =22530a(22) =2a(23) =771458a(24) =390627a(25) =106498a(26) =1062884a(27) =3039234a(28) =2a(29) =12528122