a(2n) = A060867(n+1), a(2n+1) = A092440(n+1).

Terms

a(0) =1a(1) =5a(2) =9a(3) =25a(4) =49a(5) =113a(6) =225a(7) =481a(8) =961a(9) =1985a(10) =3969a(11) =8065a(12) =16129a(13) =32513a(14) =65025a(15) =130561a(16) =261121a(17) =523265a(18) =1046529a(19) =2095105a(20) =4190209a(21) =8384513a(22) =16769025a(23) =33546241a(24) =67092481a(25) =134201345a(26) =268402689a(27) =536838145a(28) =1073676289a(29) =2147418113