a(n) = 7*n^2 + 2*n - 15.

Terms

a(0) =-6a(1) =17a(2) =54a(3) =105a(4) =170a(5) =249a(6) =342a(7) =449a(8) =570a(9) =705a(10) =854a(11) =1017a(12) =1194a(13) =1385a(14) =1590a(15) =1809a(16) =2042a(17) =2289a(18) =2550a(19) =2825a(20) =3114a(21) =3417a(22) =3734a(23) =4065a(24) =4410a(25) =4769a(26) =5142a(27) =5529a(28) =5930a(29) =6345