a(n) = 3*n^2 + 38*n - 76 (n>=2).

Terms

a(0) =12a(1) =65a(2) =124a(3) =189a(4) =260a(5) =337a(6) =420a(7) =509a(8) =604a(9) =705a(10) =812a(11) =925a(12) =1044a(13) =1169a(14) =1300a(15) =1437a(16) =1580a(17) =1729a(18) =1884a(19) =2045a(20) =2212a(21) =2385a(22) =2564a(23) =2749a(24) =2940a(25) =3137a(26) =3340a(27) =3549a(28) =3764a(29) =3985