289453domain: NPropertiesPrimalityPrimeyesAppears in sequencesPrimes p such that sigma(p+1) = sigma(p+2).at n=5A389277Primes p such that psi(p+1) = psi(p+2).at n=21A389278Number of integer compositions of n with all parts > 1 that are not the first sums of any composition.at n=28A391681Prime numbersat n=25183