G.f.: Sum_{n>=0} x^n * (1+x)^A003188(n), where A003188(n) = n XOR [n/2] is the Gray code for n.

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =6a(5) =9a(6) =23a(7) =47a(8) =65a(9) =70a(10) =111a(11) =323a(12) =902a(13) =2064a(14) =3997a(15) =6697a(16) =9638a(17) =11664a(18) =11804a(19) =11436a(20) =18903a(21) =61053a(22) =209236a(23) =623648a(24) =1610326a(25) =3685365a(26) =7673031a(27) =14926689a(28) =27784642a(29) =50202979