280601

Appears in sequences

• Strong pseudoprimes to base 2.at n=25A001262
• Pseudoquadprimes: p+4 for primes p where p+4 divides p^(p+4) + 4 and p+4 is composite.at n=25A100875
• Sarrus numbers that become prime when two is added.at n=14A137198
• Overpseudoprimes to base 2: composite k such that k = A137576((k-1)/2).at n=13A141232
• a(n) is the least base-2 overpseudoprime k such that the multiplicative order of 2 mod k equals 8*n+20.at n=8A141629
• Lesser of overpseudo-twin-primes to base 2 defined in Comment.at n=3A195468
• Pseudoprimes to a twin prime criterion of Aebi and Cairns.at n=15A224695
• Strong pseudoprimes (base 2) that become prime when two is added.at n=1A230484
• Strong pseudoprimes k to base 2 such that either k-2 or k+2 is prime.at n=9A230487
• Numbers k > 1 such that 2^k == 2 (mod k) and gcd(k, 3^k - 3) = 1.at n=10A300762
• Numbers k such that 2^(k-1) == 1 (mod k) and lpf(k)-1 does not divide k-1.at n=16A316906
• 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=14A316907
• Number of maximal subsets of {1..n} of which every subset has a different sum.at n=43A325865
• 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=8A327789