1252697

Appears in sequences

• Pseudoprimes whose prime factors do not divide any smaller pseudoprime.at n=27A084653
• Overpseudoprimes to base 2: composite k such that k = A137576((k-1)/2).at n=30A141232
• Semiprime 2-pseudoprimes of the form 10k + 7.at n=28A216667
• Numbers k > 1 such that 2^k == 2 (mod k) and gcd(k, 3^k - 3) = 1.at n=19A300762
• Numbers k such that 2^(k-1) == 1 (mod k) and lpf(k)-1 does not divide k-1.at n=30A316906
• Numbers k such that 2^(k-1) == 1 (mod k) and p-1 does not divide k-1 for every prime p dividing k.at n=27A316907
• 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=17A327789