a(n) = (A002703(n)+2)/2.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =4a(5) =8a(6) =13a(7) =24a(8) =45a(9) =82a(10) =151a(11) =282a(12) =529a(13) =992a(14) =1872a(15) =3542a(16) =6720a(17) =12788a(18) =24385a(19) =46600a(20) =89241a(21) =171197a(22) =328960a(23) =633102a(24) =1220160a(25) =2354688a(26) =4549753a(27) =8801162a(28) =17043506a(29) =33038208