a(n) = 5*a(n-1) + a(n-2) - 2*a(n-3).

Terms

a(0) =2a(1) =10a(2) =51a(3) =261a(4) =1336a(5) =6839a(6) =35009a(7) =179212a(8) =917391a(9) =4696149a(10) =24039712a(11) =123059927a(12) =629947049a(13) =3224715748a(14) =16507405935a(15) =84501851325a(16) =432567231064