a(n) = [x^n] (1 + x + x^3 + x^4)^n.

Terms

a(0) =1a(1) =1a(2) =4a(3) =17a(4) =51a(5) =136a(6) =393a(7) =1233a(8) =3865a(9) =11851a(10) =36301a(11) =112520a(12) =351352a(13) =1098189a(14) =3433704a(15) =10758609a(16) =33794505a(17) =106344793a(18) =335061790a(19) =1056924667a(20) =3338026857a(21) =10554163533a(22) =33402840615a(23) =105809430024a(24) =335444908176