a(n) = 5*a(n-1) - a(n-2) for n>1, a(0)=1, a(1)=9.

Terms

a(0) =1a(1) =9a(2) =44a(3) =211a(4) =1011a(5) =4844a(6) =23209a(7) =111201a(8) =532796a(9) =2552779a(10) =12231099a(11) =58602716a(12) =280782481a(13) =1345309689a(14) =6445765964a(15) =30883520131a(16) =147971834691a(17) =708975653324