539400

Appears in sequences

• Harmonic or Ore numbers: numbers k such that the harmonic mean of the divisors of k is an integer.at n=26A001599
• Numbers whose divisors' harmonic and arithmetic means are both integers.at n=23A007340
• Variance of time for a random walk starting at 0 to reach one of the boundaries at +n or -n for the first time.at n=30A072819
• Numbers n such that harmonic mean of the divisors of n is a prime.at n=10A074247
• Harmonic numbers (A001599) which are not perfect (A000396).at n=22A090945
• Harmonic numbers that are not multiply-perfect.at n=18A140798
• Number of different fixed (possibly) disconnected trominoes bounded (not necessarily tightly) by an n*n square.at n=24A162673
• Number of n X 6 binary arrays without the pattern 0 1 diagonally or vertically.at n=18A188840
• Number of orbits of Aut(Z^7) as function of the infinity norm n of the representative lattice point of the orbit, when the cardinality of the orbit is equal to 161280.at n=32A266395
• Numbers k such that k+1 is a prime, k+2 is twice a prime, k+3 is three times a prime, and k+4 is four times a prime.at n=22A278585
• 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=17A325022
• Harmonic numbers k such that k*p is not a harmonic number for all the primes p that do not divide k.at n=10A335369
• Numbers k such that the continued fraction of the harmonic mean of the divisors of k contains a single distinct element.at n=36A349476