a(n) = 9*a(n-2) - 4*a(n-3) for n > 2 with a(0)=1, a(1)=2.

Terms

a(0) =1a(1) =2a(2) =6a(3) =14a(4) =46a(5) =102a(6) =358a(7) =734a(8) =2814a(9) =5174a(10) =22390a(11) =35310a(12) =180814a(13) =228230a(14) =1486086a(15) =1330814a(16) =12461854a(17) =6032982a(18) =106833430a(19) =4449422a(20) =937368942a(21) =-387288922a(22) =8418522790a(23) =-7235076066a(24) =77315860798a(25) =-98789775754a(26) =724783051446