A024723(n+3)/2.

Terms

a(0) =1a(1) =1a(2) =1a(3) =3a(4) =5a(5) =7a(6) =13a(7) =25a(8) =45a(9) =81a(10) =145a(11) =291a(12) =545a(13) =1003a(14) =1897a(15) =3729a(16) =7153a(17) =13537a(18) =25881a(19) =51531a(20) =100205a(21) =192535a(22) =373637a(23) =746025a(24) =1464877a(25) =2851129a(26) =5575889a(27) =11198635a(28) =22134281a(29) =43417395