a(n+2) = 3*a(n+1) + a(n), with a(0) = 1, a(1) = 5.

Terms

a(0) =1a(1) =5a(2) =16a(3) =53a(4) =175a(5) =578a(6) =1909a(7) =6305a(8) =20824a(9) =68777a(10) =227155a(11) =750242a(12) =2477881a(13) =8183885a(14) =27029536a(15) =89272493a(16) =294847015a(17) =973813538a(18) =3216287629a(19) =10622676425a(20) =35084316904a(21) =115875627137a(22) =382711198315