a(0)=1, a(1)=5, a(n)=8*a(n-1)-a(n-2).

Terms

a(0) =1a(1) =5a(2) =39a(3) =307a(4) =2417a(5) =19029a(6) =149815a(7) =1179491a(8) =9286113a(9) =73109413a(10) =575589191a(11) =4531604115a(12) =35677243729a(13) =280886345717