a(n) = A000129(n) + n.

Terms

a(0) =0a(1) =2a(2) =4a(3) =8a(4) =16a(5) =34a(6) =76a(7) =176a(8) =416a(9) =994a(10) =2388a(11) =5752a(12) =13872a(13) =33474a(14) =80796a(15) =195040a(16) =470848a(17) =1136706a(18) =2744228a(19) =6625128a(20) =15994448a(21) =38613986a(22) =93222380a(23) =225058704a(24) =543339744a(25) =1311738146a(26) =3166815988a(27) =7645370072a(28) =18457556080a(29) =44560482178