n+A001045(n+1).

Terms

a(0) =1a(1) =2a(2) =5a(3) =8a(4) =15a(5) =26a(6) =49a(7) =92a(8) =179a(9) =350a(10) =693a(11) =1376a(12) =2743a(13) =5474a(14) =10937a(15) =21860a(16) =43707a(17) =87398a(18) =174781a(19) =349544a(20) =699071a(21) =1398122a(22) =2796225a(23) =5592428a(24) =11184835a(25) =22369646a(26) =44739269a(27) =89478512a(28) =178956999a(29) =357913970