a(n) = 2*n^2 + 3.

Terms

a(0) =3a(1) =5a(2) =11a(3) =21a(4) =35a(5) =53a(6) =75a(7) =101a(8) =131a(9) =165a(10) =203a(11) =245a(12) =291a(13) =341a(14) =395a(15) =453a(16) =515a(17) =581a(18) =651a(19) =725a(20) =803a(21) =885a(22) =971a(23) =1061a(24) =1155a(25) =1253a(26) =1355a(27) =1461a(28) =1571a(29) =1685