a(n) = 9*a(n-1) + 6*a(n-2); a(0)=0, a(1)=1.

Terms

a(0) =0a(1) =1a(2) =9a(3) =87a(4) =837a(5) =8055a(6) =77517a(7) =745983a(8) =7178949a(9) =69086439a(10) =664851645a(11) =6398183439a(12) =61572760821a(13) =592543948023