a(n) = A389802(2*n).

Terms

a(0) =1a(1) =2a(2) =3a(3) =6a(4) =13a(5) =26a(6) =55a(7) =116a(8) =241a(9) =472a(10) =873a(11) =1576a(12) =2821a(13) =5072a(14) =9173a(15) =16520a(16) =29223a(17) =50686a(18) =85763a(19) =141280a(20) =227223a(21) =357228a(22) =550167a(23) =834094a(24) =1248107a(25) =1848942a(26) =2721311a(27) =3988880a(28) =5828371a(29) =8504162