64715domain: NAppears in sequencesNumbers k that divide 8^k + 7^k + 6^k + 5^k + 4^k + 3^k + 2^k.at n=44A057490Numbers k such that 5*R_k - 2 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=10A099416Number of terms with n digits in A154780.at n=23A154779