320167

Appears in sequences

• Overpseudoprimes to base 3.at n=21A141350
• Semiprimes formed by inserting a semiprime between the semiprime's ordered factors.at n=27A227942
• The "non-residue" pseudoprimes: odd composite numbers n such that b(n)^((n-1)/2) == -1 (mod n), where base b(n) = A020649(n).at n=10A307767
• Composite numbers k == 5, 7 (mod 12) such that 3^((k-1)/2) == -1 (mod k).at n=18A375918