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) =11a(4) =26a(5) =55a(6) =108a(7) =201a(8) =360a(9) =627a(10) =1070a(11) =1799a(12) =2992a(13) =4937a(14) =8100a(15) =13235a(16) =21562a(17) =35055a(18) =56908a(19) =92289a(20) =149560a(21) =242251a(22) =392254a(23) =634991a(24) =1027776a(25) =1663345a(26) =2691748a(27) =4355771a(28) =7048250a(29) =11404807