a(n) = 144*n^2 + 12.

Terms

a(0) =12a(1) =156a(2) =588a(3) =1308a(4) =2316a(5) =3612a(6) =5196a(7) =7068a(8) =9228a(9) =11676a(10) =14412a(11) =17436a(12) =20748a(13) =24348a(14) =28236a(15) =32412a(16) =36876a(17) =41628a(18) =46668a(19) =51996a(20) =57612a(21) =63516a(22) =69708a(23) =76188a(24) =82956a(25) =90012a(26) =97356a(27) =104988a(28) =112908a(29) =121116