G.f. = b(2)*b(4)*b(6)/(x^8-x^3-x+1), where b(k) = (1-x^k)/(1-x).

Terms

a(0) =1a(1) =4a(2) =9a(3) =17a(4) =29a(5) =46a(6) =70a(7) =104a(8) =152a(9) =219a(10) =314a(11) =449a(12) =639a(13) =907a(14) =1286a(15) =1821a(16) =2576a(17) =3643a(18) =5150a(19) =7277a(20) =10281a(21) =14524a(22) =20515a(23) =28975a(24) =40923a(25) =57795a(26) =81620a(27) =115266a(28) =162780a(29) =229876