726180

Appears in sequences

• Harmonic or Ore numbers: numbers k such that the harmonic mean of the divisors of k is an integer.at n=28A001599
• Numbers whose divisors' harmonic and arithmetic means are both integers.at n=25A007340
• (1+e)-harmonic numbers: harmonic mean of (1+e)-divisors is an integer.at n=32A053783
• Harmonic numbers (A001599) which are not perfect (A000396).at n=24A090945
• a(n) = smallest number m such that m*tau(m)/sigma(m) = n, or 0 if no such m exists.at n=38A091911
• a(n) = gcd(n!, binomial(2n,n)).at n=34A135322
• Harmonic numbers that are not multiply-perfect.at n=20A140798
• Numbers k such that k divides sigma(3*k).at n=21A227303
• a(n) = binomial(2*n, n) / Product(p prime | n < p <= 2*n).at n=34A263931
• Positive integers that have a record number of divisors in Eisenstein integers.at n=44A323392
• 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=18A325022
• Harmonic numbers k such that k*p is not a harmonic number for all the primes p that do not divide k.at n=12A335369
• Numbers k such that the continued fraction of the harmonic mean of the divisors of k contains a single distinct element.at n=40A349476
• a(n) is the least number k such that A349497(k) = n, or -1 if no such k exists.at n=38A349498