a(n) = (9*n^2 - 3*n + 2)/2.

Terms

a(0) =1a(1) =4a(2) =16a(3) =37a(4) =67a(5) =106a(6) =154a(7) =211a(8) =277a(9) =352a(10) =436a(11) =529a(12) =631a(13) =742a(14) =862a(15) =991a(16) =1129a(17) =1276a(18) =1432a(19) =1597a(20) =1771a(21) =1954a(22) =2146a(23) =2347a(24) =2557a(25) =2776a(26) =3004a(27) =3241a(28) =3487a(29) =3742