a(n) = 4*n^2 + 12*n + 3.

Terms

a(0) =19a(1) =43a(2) =75a(3) =115a(4) =163a(5) =219a(6) =283a(7) =355a(8) =435a(9) =523a(10) =619a(11) =723a(12) =835a(13) =955a(14) =1083a(15) =1219a(16) =1363a(17) =1515a(18) =1675a(19) =1843a(20) =2019a(21) =2203a(22) =2395a(23) =2595a(24) =2803a(25) =3019a(26) =3243a(27) =3475a(28) =3715a(29) =3963