a(n) = a(n-1) + 9*a(n-2) for n >= 2, a(0)=1, a(1)=2.

Terms

a(0) =1a(1) =2a(2) =11a(3) =29a(4) =128a(5) =389a(6) =1541a(7) =5042a(8) =18911a(9) =64289a(10) =234488a(11) =813089a(12) =2923481a(13) =10241282a(14) =36552611a(15) =128724149a(16) =457697648a(17) =1616214989a(18) =5735493821a(19) =20281428722a(20) =71900873111a(21) =254433731609a(22) =901541589608