Constant term of the reduction of the polynomial p(n,x)=(1/2)((x+1)^n+(x-1)^n) by x^2->x+1.

Terms

a(0) =1a(1) =0a(2) =2a(3) =1a(4) =9a(5) =13a(6) =51a(7) =106a(8) =322a(9) =771a(10) =2135a(11) =5401a(12) =14445a(13) =37324a(14) =98514a(15) =256621a(16) =673933a(17) =1760997a(18) =4615823a(19) =12075526a(20) =31628466a(21) =82781215a(22) =216761547a(23) =567428401a(24) =1485645049a(25) =3889310328a(26) =10182603746a(27) =26657986681a(28) =69792188337a(29) =182717232061