10^n+7^n-1.

Terms

a(0) =1a(1) =16a(2) =148a(3) =1342a(4) =12400a(5) =116806a(6) =1117648a(7) =10823542a(8) =105764800a(9) =1040353606a(10) =10282475248a(11) =101977326742