Duplicate of A048140.

Terms

a(0) =1a(1) =2a(2) =4a(3) =8a(4) =14a(5) =27a(6) =47a(7) =86a(8) =149a(9) =261a(10) =444a(11) =760a(12) =1269a(13) =2119a(14) =3486a(15) =5711a(16) =9247a(17) =14906