a(n) = n*(2*n+5).

Terms

a(0) =0a(1) =7a(2) =18a(3) =33a(4) =52a(5) =75a(6) =102a(7) =133a(8) =168a(9) =207a(10) =250a(11) =297a(12) =348a(13) =403a(14) =462a(15) =525a(16) =592a(17) =663a(18) =738a(19) =817a(20) =900a(21) =987a(22) =1078a(23) =1173a(24) =1272a(25) =1375a(26) =1482a(27) =1593a(28) =1708a(29) =1827