a(n) = 126*2^n - 22 (n>=1).

Terms

a(0) =230a(1) =482a(2) =986a(3) =1994a(4) =4010a(5) =8042a(6) =16106a(7) =32234a(8) =64490a(9) =129002a(10) =258026a(11) =516074a(12) =1032170a(13) =2064362a(14) =4128746a(15) =8257514a(16) =16515050a(17) =33030122a(18) =66060266a(19) =132120554a(20) =264241130a(21) =528482282a(22) =1056964586a(23) =2113929194a(24) =4227858410a(25) =8455716842a(26) =16911433706a(27) =33822867434a(28) =67645734890a(29) =135291469802