a(n) = (4n + 2)^2.

Terms

a(0) =4a(1) =36a(2) =100a(3) =196a(4) =324a(5) =484a(6) =676a(7) =900a(8) =1156a(9) =1444a(10) =1764a(11) =2116a(12) =2500a(13) =2916a(14) =3364a(15) =3844a(16) =4356a(17) =4900a(18) =5476a(19) =6084a(20) =6724a(21) =7396a(22) =8100a(23) =8836a(24) =9604a(25) =10404a(26) =11236a(27) =12100a(28) =12996a(29) =13924