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

Terms

a(0) =2a(1) =5a(2) =17a(3) =56a(4) =185a(5) =611a(6) =2018a(7) =6665a(8) =22013a(9) =72704a(10) =240125a(11) =793079a(12) =2619362a(13) =8651165a(14) =28572857a(15) =94369736a(16) =311682065a(17) =1029415931a(18) =3399929858a(19) =11229205505a(20) =37087546373a(21) =122491844624a(22) =404563080245