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

Terms

a(0) =3a(1) =15a(2) =76a(3) =386a(4) =1961a(5) =9963a(6) =50618a(7) =257170a(8) =1306579a(9) =6638211a(10) =33726124a(11) =171349094a(12) =870556961a(13) =4422955527a(14) =22471287314a(15) =114167721214a(16) =580041026803