a(n+3) = 5*a(n+2)-4*a(n+1)+a(n).

Terms

a(0) =0a(1) =1a(2) =2a(3) =6a(4) =23a(5) =93a(6) =379a(7) =1546a(8) =6307a(9) =25730a(10) =104968a(11) =428227a(12) =1746993a(13) =7127025a(14) =29075380a(15) =118615793a(16) =483904470a(17) =1974134558a(18) =8053670703a(19) =32855719753a(20) =134038050511a(21) =546821044246