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) =2a(3) =6a(4) =15a(5) =34a(6) =70a(7) =135a(8) =248a(9) =440a(10) =761a(11) =1292a(12) =2164a(13) =3589a(14) =5910a(15) =9682a(16) =15803a(17) =25726a(18) =41802a(19) =67835a(20) =109980a(21) =178196a(22) =288597a(23) =467256a(24) =756360a(25) =1224169a(26) =1981130a(27) =3205950a(28) =5187783a(29) =8394490