1999999998domain: NAppears in sequencesNumber of nonzero palindromes less than 10^n.at n=17A050250Numbers k such that 4*k-1 is the digit reversal of k-1.at n=18A083812a(n) = 2*(10^n - 1).at n=9A086573(10^n-1) * (n+9) / 9.at n=9A091692a(n) = 111111111 * n.at n=17A172525