558877domain: NAppears in sequencesPositive integers k such that k divides 12^k - 1.at n=16A014951Numbers k such that k | 10^k + 1.at n=22A015958Numbers k that divide 6^k + 5^k.at n=25A045595Numbers n dividing u(n), where the Lucas sequence is defined u(i) = u(i-1) - 3*u(i-2) with initial conditions u(0)=0, u(1)=1.at n=18A228440