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

Terms

a(0) =4a(1) =64a(2) =196a(3) =400a(4) =676a(5) =1024a(6) =1444a(7) =1936a(8) =2500a(9) =3136a(10) =3844a(11) =4624a(12) =5476a(13) =6400a(14) =7396a(15) =8464a(16) =9604a(17) =10816a(18) =12100a(19) =13456a(20) =14884a(21) =16384a(22) =17956a(23) =19600a(24) =21316a(25) =23104a(26) =24964a(27) =26896a(28) =28900a(29) =30976