a(n) = 16*n^3 - 36*n^2 + 30*n - 9.

Terms

a(0) =1a(1) =35a(2) =189a(3) =559a(4) =1241a(5) =2331a(6) =3925a(7) =6119a(8) =9009a(9) =12691a(10) =17261a(11) =22815a(12) =29449a(13) =37259a(14) =46341a(15) =56791a(16) =68705a(17) =82179a(18) =97309a(19) =114191a(20) =132921a(21) =153595a(22) =176309a(23) =201159a(24) =228241a(25) =257651a(26) =289485a(27) =323839a(28) =360809a(29) =400491