98233domain: NAppears in sequencesNumber of nonempty subsets of {1, 2, ..., n} with GCD equal to 1 and containing the sum of any two elements whenever it is at most n.at n=28A358392Semiprimes k such that k+4, k+6, k+9, k+10 and k+14 are also semiprimes.at n=27A360666