871416

Appears in sequences

• Numbers n such that (n, sigma(n)) lies on the hyperbola y^2 - x^2 = m^2, for some natural number m, i.e., sigma(n)^2 - n^2 = m^2.at n=5A066784
• Numbers k for which sigma(k)/k - 4/7 is an integer.at n=4A218411
• Numbers n such that the set of prime divisors of n is equal to the set of prime divisors of sum of proper divisors of n while n is not in A027598.at n=32A286876
• Positive integers that have a record number of divisors in Eisenstein integers.at n=45A323392
• a(n) = A000203(A344422(n)).at n=13A345260
• Numbers k for which k * gcd(sigma(k), u) is equal to sigma(k) * gcd(k, u), where u is obtained by shifting the prime factorization of k two steps toward larger primes [with u = A003961(A003961(k))].at n=5A349746