a(n) = Sum_{d|n, d odd} d^d.

Terms

a(0) =1a(1) =1a(2) =28a(3) =1a(4) =3126a(5) =28a(6) =823544a(7) =1a(8) =387420517a(9) =3126a(10) =285311670612a(11) =28a(13) =823544a(15) =1a(17) =387420517a(19) =3126a(21) =285311670612