a(n) = n^3*Product_{distinct primes p dividing n} (1+1/p^3).

Terms

a(0) =1a(1) =9a(2) =28a(3) =72a(4) =126a(5) =252a(6) =344a(7) =576a(8) =756a(9) =1134a(10) =1332a(11) =2016a(12) =2198a(13) =3096a(14) =3528a(15) =4608a(16) =4914a(17) =6804a(18) =6860a(19) =9072a(20) =9632a(21) =11988a(22) =12168a(23) =16128a(24) =15750a(25) =19782a(26) =20412a(27) =24768a(28) =24390a(29) =31752