Linear 2nd order recurrence: a(n) = 4*a(n-1) + 5*a(n-2).

Terms

a(0) =0a(1) =1a(2) =4a(3) =21a(4) =104a(5) =521a(6) =2604a(7) =13021a(8) =65104a(9) =325521a(10) =1627604a(11) =8138021a(12) =40690104a(13) =203450521a(14) =1017252604a(15) =5086263021a(16) =25431315104a(17) =127156575521a(18) =635782877604