131013domain: NAppears in sequencesConcatenations of pairs of primes that differ by 1000.at n=0A103534Difference between the powers of two and the primes.at n=16A111209Let p*q = A006881(n) be the n-th number that is the product of two distinct primes, with p = prime(i), q=prime(j); a(n) = p^j - q^i.at n=33A176885