597530domain: NAppears in sequencesPrime(prime(n))^2+1.at n=32A092774Numbers 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=30A166388Numbers k of the form p^2 + 1 (for prime p) where k^2 + 1 is also prime.at n=22A235053Numbers m such that sigma(m-1) is a prime.at n=31A270413