63857domain: NPropertiesPrimalityPrimeyesAppears in sequencesNumbers n such that 6*10^n + 7*R_n - 4 is prime, where R_n = 11...1 is the repunit (A002275) of length n.at n=9A103042Primes p such that the concatenation of p and 29 is a square number: "p 29" = N = m^2.at n=31A168545Prime numbersat n=6405