1421280

Appears in sequences

• Harmonic or Ore numbers: numbers k such that the harmonic mean of the divisors of k is an integer.at n=32A001599
• Numbers whose divisors' harmonic and arithmetic means are both integers.at n=28A007340
• Numbers n such that harmonic mean of the divisors of n is a prime.at n=11A074247
• Harmonic numbers (A001599) which are not perfect (A000396).at n=28A090945
• Harmonic numbers that are not multiply-perfect.at n=24A140798
• Numbers n such that sigma(n+sigma(n)) = 5*sigma(n).at n=28A246912
• Imaginary part of n!*Sum_{k=1..n} i^(k-1)/k, where i is sqrt(-1).at n=9A282132
• 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=22A325022
• Harmonic numbers (A001599) with a record harmonic mean of divisors.at n=15A335316
• Harmonic numbers k such that k*p is not a harmonic number for all the primes p that do not divide k.at n=14A335369
• Bi-unitary arithmetic numbers k whose mean bi-unitary divisor is a bi-unitary divisor of k.at n=34A361787