a(n) = a(n-1) + 7*a(n-2) for n >= 2, a(0)=1, a(1)=2.

Terms

a(0) =1a(1) =2a(2) =9a(3) =23a(4) =86a(5) =247a(6) =849a(7) =2578a(8) =8521a(9) =26567a(10) =86214a(11) =272183a(12) =875681a(13) =2780962a(14) =8910729a(15) =28377463a(16) =90752566a(17) =289394807a(18) =924662769a(19) =2950426418a(20) =9423065801a(21) =30076050727a(22) =96037511334a(23) =306569866423a(24) =978832445761