G.f. = b(2)^2*b(6)/(x^7+x^6-x^5-x^2-x+1), where b(k) = (1-x^k)/(1-x).

Terms

a(0) =1a(1) =4a(2) =9a(3) =17a(4) =30a(5) =52a(6) =88a(7) =145a(8) =237a(9) =386a(10) =628a(11) =1020a(12) =1653a(13) =2677a(14) =4334a(15) =7016a(16) =11356a(17) =18377a(18) =29737a(19) =48118a(20) =77860a(21) =125984a(22) =203849a(23) =329837a(24) =533690a(25) =863532a(26) =1397228a(27) =2260765a(28) =3657997a(29) =5918766