G.f. = b(2)*b(6)*b(10)/(x^14+x^12-x^5-x^3-x+1), where b(k) = (1-x^k)/(1-x).

Terms

a(0) =1a(1) =4a(2) =9a(3) =17a(4) =30a(5) =51a(6) =84a(7) =135a(8) =215a(9) =341a(10) =538a(11) =846a(12) =1328a(13) =2082a(14) =3262a(15) =5108a(16) =7997a(17) =12519a(18) =19595a(19) =30668a(20) =47996a(21) =75112a(22) =117546a(23) =183950a(24) =287864a(25) =450478a(26) =704950a(27) =1103170a(28) =1726339a(29) =2701526