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

Terms

a(0) =1a(1) =5a(2) =17a(3) =61a(4) =217a(5) =773a(6) =2753a(7) =9805a(8) =34921a(9) =124373a(10) =442961a(11) =1577629a(12) =5618809a(13) =20011685a(14) =71272673a(15) =253841389a(16) =904069513a(17) =3219891317a(18) =11467812977a(19) =40843221565a(20) =145465290649a(21) =518082315077