a(n) = 12*n^2 - 2*n - 1.

Terms

a(0) =-1a(1) =9a(2) =43a(3) =101a(4) =183a(5) =289a(6) =419a(7) =573a(8) =751a(9) =953a(10) =1179a(11) =1429a(12) =1703a(13) =2001a(14) =2323a(15) =2669a(16) =3039a(17) =3433a(18) =3851a(19) =4293a(20) =4759a(21) =5249a(22) =5763a(23) =6301a(24) =6863a(25) =7449a(26) =8059a(27) =8693a(28) =9351a(29) =10033