146690domain: NAppears in sequencesa(n) = 6561*n^2 - 3564*n + 485.at n=5A156774Numbers of the form q-p, where p and q are prime and q = p^0+p^1+p^2+..+p^k for some k.at n=23A166388Numbers m such that sigma(m-1) is a prime.at n=23A270413Numbers n such that sigma(n-1) and sigma(n) - 1 are both primes.at n=7A270415