a(0)=1, a(n+1) = 5*a(n)-4*A117641(n) for n>=0.

Terms

a(0) =1a(1) =1a(2) =5a(3) =21a(4) =93a(5) =421a(6) =1937a(7) =9017a(8) =42349a(9) =200277a(10) =952425a(11) =4549953a(12) =21818841a(13) =104966889a(14) =506372277a(15) =2448641061a(16) =11865563853a(17) =57604036309a(18) =280110716777