2290260

Appears in sequences

• Numbers whose divisors' harmonic and arithmetic means are both integers.at n=31A007340
• Numbers n such that harmonic mean of the divisors of n is a prime.at n=13A074247
• a(n) = smallest number m such that m*tau(m)/sigma(m) = n, or 0 if no such m exists.at n=40A091911
• Harmonic numbers that are not multiply-perfect.at n=27A140798
• Harmonic numbers m from A001599 such that m*(m-tau(m))/sigma(m) is not an integer, where k-tau(k) = the number of nondivisors of k (A049820), tau(k) = the number of divisors of k (A000005) and sigma(k) = the sum of the divisors of k (A000203).at n=25A325022
• Harmonic numbers k such that k*p is not a harmonic number for all the primes p that do not divide k.at n=17A335369