753480
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=29A001599
- Numbers whose divisors' harmonic and arithmetic means are both integers.at n=26A007340
- Expansion of e.g.f.: cosh(tanh(x)*log(1+x)).at n=10A009172
- Numbers k such that the least term in the periodic part of the continued fraction for sqrt(k) is 31.at n=27A031709
- Harmonic numbers (A001599) which are not perfect (A000396).at n=25A090945
- Numbers that can be expressed as the difference of the squares of primes in exactly eleven distinct ways.at n=21A092007
- Triangular sequence of coefficients of p(x,t) = t*exp(3*x*t - t^2)/(exp(t) - 1).at n=16A137784
- Harmonic numbers that are not multiply-perfect.at n=21A140798
- a(n) = 961*n^2 + 2*n.at n=27A158413
- Triangle of Generalized Runyon numbers R_{n,k}^(3) read by rows.at n=41A173020
- Numbers with prime factorization pqrst^2u^3.at n=9A190390
- a(n) = lcm(A225627(n),p1,p2,...,pk) for such a partition {p1+p2+...+pk} of n which maximizes this value among all partitions of n.at n=23A225628
- a(n) is the first common term in column n of tables A225630 and A225640, when scanned from the top to bottom.at n=23A226055
- a(n) = 3*n*(3*n + 1)*(3*n + 2).at n=29A228889
- Numbers x such that there exist a pair y, n with x < y, x != n and y != n that makes {x,y,n,n} an amicable multiset.at n=1A273970
- 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=19A325022
- Harmonic numbers k such that k*p is not a harmonic number for all the primes p that do not divide k.at n=13A335369
- Numbers k such that A122111(k) [conjugated prime factorization of k] is one of Ore's Harmonic numbers (in A001599).at n=28A336317
- Numbers k such that both k and A122111(k) [its conjugated prime factorization] are Ore's Harmonic numbers (A001599).at n=2A336397
- Numbers k such that the continued fraction of the harmonic mean of the divisors of k contains a single distinct element.at n=41A349476