a(n) = 9*7^n+1.

Terms

a(0) =10a(1) =64a(2) =442a(3) =3088a(4) =21610a(5) =151264a(6) =1058842a(7) =7411888a(8) =51883210a(9) =363182464a(10) =2542277242a(11) =17795940688a(12) =124571584810a(13) =872001093664