122921

Properties

Appears in sequences

• Number of N-equivalence classes of self-dual threshold functions of n or fewer variables.at n=6A002080
• a(n) = largest noncomposite factor of 2^(2n+1) - 1.at n=17A002588
• Divisors of 2^35 - 1.at n=7A003542
• Largest prime factor of 2^n - 1.at n=33A005420
• Primes of form prime(1) + ... + prime(k) + 1.at n=26A053845
• Primes which can be represented as the sum of a square and its reverse.at n=22A072383
• For p = prime(n), a(n) is the largest prime q such that pq is a base-2 pseudoprime; that is, 2^(pq-1) = 1 mod pq; a(n) is 0 if no such prime exists.at n=18A086019
• Largest primitive prime factor of 2^n-1, or a(n) = 1 if no such prime exists.at n=34A097406
• Sort the primes (except 2) according to the multiplicative order of 2 modulo that prime. If two primes have the same order of 2, they are arranged numerically.at n=39A108974
• Irregular triangle in which row n has all primes q such that prime(n)*q is a base-2 Fermat pseudoprime.at n=28A180471
• Primes p such that (p-1)/ord(2,p) > (q-1)/ord(2,q) for odd primes q < p.at n=16A226216
• Primitive prime factors of the cyclotomic polynomial sequence Phi(7,k) in the order in which they occur.at n=37A256146
• Largest prime factor of 4^n - 1.at n=34A274906
• a(n) = largest prime q such that q | 2^p - 2 and p - 1 | q - 1, where p = prime(n).at n=19A287945
• Primes p = x^2 + y^2, not of the form z^2 + 1, such that 2^(x^2) == 2^(y^2) == 1 (mod p).at n=17A299103
• a(n) is the largest prime factor of 2^(prime(n) - 1) - 1.at n=18A358699
• Prime numbersat n=11557