n^3 + 4*n^2 - 5*n + 1.

Terms

a(0) =1a(1) =1a(2) =15a(3) =49a(4) =109a(5) =201a(6) =331a(7) =505a(8) =729a(9) =1009a(10) =1351a(11) =1761a(12) =2245a(13) =2809a(14) =3459a(15) =4201a(16) =5041a(17) =5985a(18) =7039a(19) =8209a(20) =9501a(21) =10921a(22) =12475a(23) =14169a(24) =16009a(25) =18001a(26) =20151a(27) =22465a(28) =24949a(29) =27609