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

Terms

a(0) =1a(1) =3a(2) =19a(3) =137a(4) =1001a(5) =7323a(6) =53579a(7) =392017a(8) =2868241a(9) =20985843a(10) =153545539a(11) =1123435097a(12) =8219753081a(13) =60140849163a(14) =440028027899