a(n) = Sum_{d|n} binomial(n,d)^3.

Terms

a(0) =1a(1) =9a(2) =28a(3) =281a(4) =126a(5) =11592a(6) =344a(7) =365465a(8) =593434a(9) =16095134a(10) =1332a(11) =921113624a(12) =2198a(13) =40424993884a(14) =27175280778a(16) =4914a(18) =6860a(22) =12168