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

Terms

a(0) =2a(1) =3a(2) =13a(3) =62a(4) =297a(5) =1423a(6) =6818a(7) =32667a(8) =156517a(9) =749918a(10) =3593073a(11) =17215447a(12) =82484162a(13) =395205363a(14) =1893542653a(15) =9072507902a(16) =43468996857a(17) =208272476383a(18) =997893385058