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

Terms

a(0) =5a(1) =21a(2) =95a(3) =433a(4) =1975a(5) =9009a(6) =41095a(7) =187457a(8) =855095a(9) =3900561a(10) =17792615a(11) =81161953a(12) =370224535a(13) =1688798769a(14) =7703544775a(15) =35140126337a(16) =160293542135a(17) =731187458001