121369

Properties

Appears in sequences

• A nonlinear binomial sum.at n=22A000126
• a(n) = largest noncomposite factor of 2^(2n+1) - 1.at n=19A002588
• Divisors of 2^39 - 1.at n=6A003545
• Largest prime factor of 2^n - 1.at n=37A005420
• Largest primitive prime factor of 2^n-1, or a(n) = 1 if no such prime exists.at n=38A097406
• Primes of the form 20*k^2 + 36*k + 17.at n=29A154419
• Prime divisors of 2^1092-1, listed with multiplicities.at n=30A172290
• Irregular triangle in which row n has all primes q such that prime(n)*q is a base-2 Fermat pseudoprime.at n=36A180471
• Antidiagonal sums of triangle A186084.at n=43A186505
• Primes p such that (p-1)/ord(2,p) > (q-1)/ord(2,q) for odd primes q < p.at n=15A226216
• Least prime divisor of the n-th tangent number T_n which does not divide any T_k with k < n, or 1 if such a primitive prime divisor of T_n does not exist.at n=38A242195
• Prime divisors of 2^3510-1, listed with multiplicities.at n=30A242715
• Terms in A261524 that are not multiples of earlier terms.at n=14A261862
• Largest prime factor of 8^n - 1.at n=12A274908
• a(n) = largest prime q such that q | 2^p - 2 and p - 1 | q - 1, where p = prime(n).at n=36A287945
• 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=16A299103
• Common prime factors of A007663(183)/1093 and A007663(490)/3511.at n=5A343763
• Prime numbersat n=11424