22366891

Properties

Appears in sequences

• Smallest primitive factor of 2^(2n+1) + 1.at n=19A002185
• Largest primitive factor of 2^(2n+1) + 1.at n=19A002589
• 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=20A086019
• Sylvester-Jacobsthal cyclotomic numbers.at n=38A105603
• a(n) = Sum_{k=floor((n+1)/2)..n} J(k+1), J(k) = A001045(k).at n=24A129362
• List of primitive prime divisors of the Jacobsthal numbers A001045 in their order of occurrence.at n=44A129738
• Primes which divide none of overpseudoprimes to base 2 (A141232).at n=34A144755
• Aurifeuillian primes of the form 2^k+1.at n=19A153443
• Primes in A153601.at n=29A153602
• Numbers k (between 2^(m-1) and 2^m) such that 2^(k-1) == 1 (mod k) and 2^(k-1-m) == k - 2^p (mod k) for some p > 0 with 2^p < k.at n=39A167612
• Prime divisors of 2^1092-1, listed with multiplicities.at n=35A172290
• Irregular triangle in which row n has all primes q such that prime(n)*q is a base-2 Fermat pseudoprime.at n=37A180471
• Primes of the form Phi(phi(k),2), the phi(k)-th cyclotomic polynomial evaluated at 2, where phi is the Euler totient function.at n=14A211876
• Prime divisors of 2^3510-1, listed with multiplicities.at n=40A242715
• a(n) = (1^n + (-2)^n + 4^n)/3.at n=13A245489
• Largest prime factor of the n-th Jacobsthal number, A001045(n).at n=36A271314
• Largest prime factor of 8^n + 1.at n=13A274905
• Largest prime factor of 4^n - 1.at n=38A274906
• Largest prime factor of 8^n - 1.at n=25A274908
• a(n) = largest prime q such that q | 2^p - 2 and p - 1 | q - 1, where p = prime(n).at n=21A287945