680627

Appears in sequences

• Pseudoprimes whose prime factors do not divide any smaller pseudoprime.at n=20A084653
• For p = prime(n), a(n) is the smallest base-2 pseudoprime N (that is, 2^(N-1) = 1 mod N) such that p divides N.at n=26A085999
• Pseudoquadprimes: p+4 for primes p where p+4 divides p^(p+4) + 4 and p+4 is composite.at n=33A100875
• Pseudoprimes to base 2 of the form 4k+3.at n=27A177884
• Semiprime 2-pseudoprimes of the form 10k + 7.at n=21A216667
• Pseudoprimes congruent to 7 mod 10.at n=25A317972
• a(n) is the smallest Fermat pseudoprime to base 2 such that gpf(p-1) = prime(n) for all prime factors p of a(n).at n=15A327789