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

Terms

a(0) =3a(1) =7a(2) =15a(3) =27a(4) =43a(5) =63a(6) =87a(7) =115a(8) =147a(9) =183a(10) =223a(11) =267a(12) =315a(13) =367a(14) =423a(15) =483a(16) =547a(17) =615a(18) =687a(19) =763a(20) =843a(21) =927a(22) =1015a(23) =1107a(24) =1203a(25) =1303a(26) =1407a(27) =1515a(28) =1627a(29) =1743