17966519domain: NAppears in sequencesSquarefree composite numbers n such that p^2 - 1 divides n^2 - 1 for every prime p dividing n.at n=9A287119Composite squarefree numbers k such that k^2-1 is divisible by p-1 and p+1, where p are all the prime factors of k.at n=28A306685