480853domain: NPropertiesPrimalityPrimeyesAppears in sequencesa(n) is the least number k such that exactly fraction 1/n of the members of the reduced residue system mod k are prime, or 0 if there is no such k.at n=10A307711Primes p such that primepi(p)-1 divides p-1.at n=14A359044Prime numbersat n=40072