a(n) = Sum_{k=1..n-1} sigma_3(k)*sigma_9(n-k).

Terms

a(0) =0a(1) =1a(2) =522a(3) =24329a(4) =454250a(5) =4905766a(6) =36532244a(7) =207705929a(8) =961214238a(9) =3784166376a(10) =13066960126a(11) =40511160326a(12) =114681233758a(13) =300599979884a(14) =737035375772