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) =14a(4) =37a(5) =84a(6) =172a(7) =329a(8) =600a(9) =1058a(10) =1821a(11) =3080a(12) =5144a(13) =8513a(14) =13996a(15) =22902a(16) =37349a(17) =60764a(18) =98692a(19) =160105a(20) =259520a(21) =420426a(22) =680829a(23) =1102224a(24) =1784112a(25) =2887489a(26) =4672852a(27) =7561694a(28) =12236005a(29) =19799268