Coefficient of x in the reduction by x^2 -> x+1 of the polynomial p(n,x) defined at Comments.

Terms

a(0) =0a(1) =1a(2) =3a(3) =12a(4) =33a(5) =77a(6) =160a(7) =309a(8) =567a(9) =1004a(10) =1733a(11) =2937a(12) =4912a(13) =8137a(14) =13387a(15) =21916a(16) =35753a(17) =58181a(18) =94512a(19) =153341a(20) =248575a(21) =402716a(22) =652173a(23) =1055857a(24) =1709088a(25) =2766097a(26) =4476435a(27) =7243884a(28) =11721777a(29) =18967229