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) =11a(4) =40a(5) =115a(6) =280a(7) =611a(8) =1234a(9) =2357a(10) =4320a(11) =7677a(12) =13328a(13) =22733a(14) =38258a(15) =63735a(16) =105368a(17) =173199a(18) =283480a(19) =462511a(20) =752850a(21) =1223361a(22) =1985472a(23) =3219481a(24) =5217120a(25) =8450425a(26) =13683170a(27) =22151171a(28) =35854024a(29) =58027147