a(n) = 2^(n-1) + 2^[ n/2 ] + 2^[ (n-1)/2 ] - F(n+3).

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =3a(6) =10a(7) =25a(8) =63a(9) =144a(10) =327a(11) =711a(12) =1534a(13) =3237a(14) =6787a(15) =14056a(16) =28971a(17) =59283a(18) =120894a(19) =245457a(20) =497167a(21) =1004256a(22) =2025199a(23) =4077007a(24) =8198334a(25) =16467597a(26) =33052491a(27) =66293208