a(n) = floor( (4 + sqrt(11))^n ).

Terms

a(0) =1a(1) =7a(2) =53a(3) =391a(4) =2865a(5) =20967a(6) =153413a(7) =1122471a(8) =8212705a(9) =60089287a(10) =439650773a(11) =3216759751a(12) =23535824145a(13) =172202794407