87511domain: NPropertiesPrimalityPrimeyesAppears in sequencesNumber of positive integers <= 2^n of form x^2 + 4 y^2.at n=19A000072Numbers k such that 1 + product of first k composite numbers is prime.at n=25A053982n is prime and is the sum of the first k primes for some k, start from 5.at n=15A155851Prime numbersat n=8494