a(2n) = A002315(n), a(2n+1) = A082639(n+1).

Terms

a(0) =1a(1) =2a(2) =7a(3) =16a(4) =41a(5) =98a(6) =239a(7) =576a(8) =1393a(9) =3362a(10) =8119a(11) =19600a(12) =47321a(13) =114242a(14) =275807a(15) =665856a(16) =1607521a(17) =3880898a(18) =9369319a(19) =22619536a(20) =54608393a(21) =131836322a(22) =318281039a(23) =768398400a(24) =1855077841a(25) =4478554082a(26) =10812186007a(27) =26102926096a(28) =63018038201