167400
domain: N
Appears in sequences
- Harmonic or Ore numbers: numbers k such that the harmonic mean of the divisors of k is an integer.at n=20A001599
- Numbers whose divisors' harmonic and arithmetic means are both integers.at n=17A007340
- Numbers k such that the set of prime divisors of k is equal to the set of prime divisors of sigma(k).at n=25A027598
- Numbers k such that (k, phi(k), sigma(k)) lies on a sphere with integral radius centered at the origin, i.e., k^2 + phi(k)^2 + sigma(k)^2 is a square.at n=11A066785
- Harmonic numbers (A001599) which are not perfect (A000396).at n=16A090945
- a(n) = smallest number m such that m*tau(m)/sigma(m) = n, or 0 if no such m exists.at n=26A091911
- Harmonic numbers that are not multiply-perfect.at n=12A140798
- Corresponding values of arithmetic means of divisors of numbers from A007340.at n=40A157848
- a(n) = the smallest natural numbers m such that product of harmonic mean of the divisors of n and harmonic mean of the divisors of m are integers.at n=52A176802
- Numbers with prime factorization pq^2r^3s^3.at n=19A190320
- Triangle of earliest friendly numbers having n friends.at n=22A211679
- Triangle of earliest friendly numbers having n friends.at n=29A211679
- Numbers k for which sigma(k)/k - 5/9 is an integer.at n=3A218416
- Number of nonisomorphic proper colorings of partition multicycle graph using six colors.at n=94A298266
- 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=12A325022
- Numbers k such that A048675(sigma(k)) is equal to A048675(2*k).at n=20A331751
- Numbers k such that squarefree part of sigma(k) is equal to squarefree part of 2*k.at n=24A331752
- Numbers k such that the squarefree kernel of sigma(k) is equal to the squarefree kernel of 2*k.at n=26A332208
- Harmonic numbers (A001599) with a record harmonic mean of divisors.at n=11A335316
- Numbers k for which A065330(k) = A065330(sigma(k)).at n=24A336458