Coefficient of x in the reduction by x^2->x+1 of the polynomial p(n,x) defined below in Comments.

Terms

a(0) =0a(1) =1a(2) =4a(3) =9a(4) =18a(5) =33a(6) =58a(7) =99a(8) =166a(9) =275a(10) =452a(11) =739a(12) =1204a(13) =1957a(14) =3176a(15) =5149a(16) =8342a(17) =13509a(18) =21870a(19) =35399a(20) =57290a(21) =92711a(22) =150024a(23) =242759a(24) =392808a(25) =635593a(26) =1028428a(27) =1664049a(28) =2692506a(29) =4356585