Bisection of A000930.

Terms

a(0) =1a(1) =1a(2) =3a(3) =6a(4) =13a(5) =28a(6) =60a(7) =129a(8) =277a(9) =595a(10) =1278a(11) =2745a(12) =5896a(13) =12664a(14) =27201a(15) =58425a(16) =125491a(17) =269542a(18) =578949a(19) =1243524a(20) =2670964a(21) =5736961a(22) =12322413a(23) =26467299a(24) =56849086a(25) =122106097a(26) =262271568a(27) =563332848a(28) =1209982081a(29) =2598919345