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A348697 Numbers m such that there is at least two smaller numbers k < m with the same harmonic mean of divisors as m. 1
321048, 448335, 1284192, 1605240, 1672125, 1862190, 3531528, 5016375, 5457816, 6420960, 7384104, 7621695, 8026200, 9310392, 9952488, 10311705, 11878776, 13001715, 13035330, 13162968, 13805064, 13898385, 14126112, 15089256, 16588395, 17015544, 17657640, 17836000 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
What is the least term m with more than two smaller numbers k with the same harmonic mean of divisors as m?
LINKS
EXAMPLE
321048 is a term since the harmonic mean of divisors of 321048 is 3528/125, and it is also the harmonic mean of divisors of both 201096 and 296352 which are smaller than 321048.
MATHEMATICA
h = Table[DivisorSigma[0, n]/DivisorSigma[-1, n], {n, 1, 2*10^6}]; i = Position[(t = Tally[h])[[;; , 2]], _?(# > 2 &)] // Flatten; Position[h, #][[3 ;; -1]] & /@ t[[i, 1]] // Flatten // Sort
CROSSREFS
Sequence in context: A205931 A236318 A348827 * A097937 A244565 A362874
KEYWORD
nonn
AUTHOR
Amiram Eldar, Oct 30 2021
STATUS
approved

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Last modified May 23 05:11 EDT 2024. Contains 372758 sequences. (Running on oeis4.)