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

Terms

a(0) =3a(1) =5a(2) =9a(3) =15a(4) =23a(5) =33a(6) =45a(7) =59a(8) =75a(9) =93a(10) =113a(11) =135a(12) =159a(13) =185a(14) =213a(15) =243a(16) =275a(17) =309a(18) =345a(19) =383a(20) =423a(21) =465a(22) =509a(23) =555a(24) =603a(25) =653a(26) =705a(27) =759a(28) =815a(29) =873