a(n) = (9*n^2 + 9*n - 16)/2.

Terms

a(0) =1a(1) =19a(2) =46a(3) =82a(4) =127a(5) =181a(6) =244a(7) =316a(8) =397a(9) =487a(10) =586a(11) =694a(12) =811a(13) =937a(14) =1072a(15) =1216a(16) =1369a(17) =1531a(18) =1702a(19) =1882a(20) =2071a(21) =2269a(22) =2476a(23) =2692a(24) =2917a(25) =3151a(26) =3394a(27) =3646a(28) =3907a(29) =4177