a(n) = (n-1)! * (10^n - 1) / 9.A323416a(n) = (n-1)! * (10^n - 1) / 9.Terms a(0) =1a(1) =11a(2) =222a(3) =6666a(4) =266664a(5) =13333320a(6) =799999920a(7) =55999999440External referencesoeis: A323416