1099999989domain: NAppears in sequencesNumbers k such that 9*k = (k written backwards), k > 0.at n=10A001232Numbers k such that k written backwards is a nontrivial multiple of k.at n=18A008919Repunits with even indices multiplied by 99, i.e., 99*(11, 1111, 111111, 11111111, ...).at n=3A274755