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

Terms

a(0) =4a(1) =5a(2) =40a(3) =185a(4) =940a(5) =4685a(6) =23440a(7) =117185a(8) =585940a(9) =2929685a(10) =14648440a(11) =73242185a(12) =366210940a(13) =1831054685a(14) =9155273440a(15) =45776367185a(16) =228881835940