Constant term in the reduction of the n-th Fibonacci polynomial by x^3->x^2+3x+1. See Comments.

Terms

a(0) =1a(1) =0a(2) =1a(3) =1a(4) =2a(5) =8a(6) =14a(7) =55a(8) =121a(9) =392a(10) =989a(11) =2912a(12) =7797a(13) =22104a(14) =60553a(15) =169289a(16) =467622a(17) =1300888a(18) =3603914a(19) =10008543a(20) =27755249a(21) =77034176a(22) =213702153a(23) =593005504a(24) =1645265209a(25) =4565154816a(26) =12666317073a(27) =35144684065a(28) =97512548090a(29) =270561677224