a(n) = 6*11^n - 1.

Terms

a(0) =5a(1) =65a(2) =725a(3) =7985a(4) =87845a(5) =966305a(6) =10629365a(7) =116923025a(8) =1286153285a(9) =14147686145a(10) =155624547605