a(n) = (12*n + 6)^2.

Terms

a(0) =36a(1) =324a(2) =900a(3) =1764a(4) =2916a(5) =4356a(6) =6084a(7) =8100a(8) =10404a(9) =12996a(10) =15876a(11) =19044a(12) =22500a(13) =26244a(14) =30276a(15) =34596a(16) =39204a(17) =44100a(18) =49284a(19) =54756a(20) =60516a(21) =66564a(22) =72900a(23) =79524a(24) =86436a(25) =93636a(26) =101124a(27) =108900a(28) =116964