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) =4a(3) =12a(4) =29a(5) =62a(6) =122a(7) =227a(8) =406a(9) =706a(10) =1203a(11) =2020a(12) =3356a(13) =5533a(14) =9072a(15) =14816a(16) =24129a(17) =39218a(18) =63654a(19) =103215a(20) =167250a(21) =270886a(22) =438599a(23) =709992a(24) =1149144a(25) =1859737a(26) =3009532a(27) =4869972a(28) =7880261a(29) =12751046