a(n) = (2*n+1)*(2*n+3)*(2*n+5).

Terms

a(0) =15a(1) =105a(2) =315a(3) =693a(4) =1287a(5) =2145a(6) =3315a(7) =4845a(8) =6783a(9) =9177a(10) =12075a(11) =15525a(12) =19575a(13) =24273a(14) =29667a(15) =35805a(16) =42735a(17) =50505a(18) =59163a(19) =68757a(20) =79335a(21) =90945a(22) =103635a(23) =117453a(24) =132447a(25) =148665a(26) =166155a(27) =184965a(28) =205143a(29) =226737