a(n) = (2*n + 1) * 2^(n + 1).

Terms

a(0) =2a(1) =12a(2) =40a(3) =112a(4) =288a(5) =704a(6) =1664a(7) =3840a(8) =8704a(9) =19456a(10) =43008a(11) =94208a(12) =204800a(13) =442368a(14) =950272a(15) =2031616a(16) =4325376a(17) =9175040a(18) =19398656a(19) =40894464a(20) =85983232a(21) =180355072a(22) =377487360a(23) =788529152a(24) =1644167168a(25) =3422552064a(26) =7113539584a(27) =14763950080a(28) =30601641984a(29) =63350767616