a(n) = 2*a(n-1) - a(n-2) + 2*a(n-3) - a(n-4) + a(n-5), n > 5.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =4a(6) =8a(7) =16a(8) =31a(9) =60a(10) =117a(11) =228a(12) =444a(13) =865a(14) =1685a(15) =3282a(16) =6393a(17) =12453a(18) =24257a(19) =47250a(20) =92038a(21) =179280a(22) =349218a(23) =680239a(24) =1325032a(25) =2581019a(26) =5027546a(27) =9793116a(28) =19075931a(29) =37157851