A348696 Numbers m such that there is at least one smaller number k < m with the same harmonic mean of divisors as m.
135, 224, 496, 936, 1485, 1488, 1755, 2295, 2464, 2565, 2912, 3105, 3808, 3915, 4185, 4256, 4464, 4680, 4995, 5152, 5456, 5535, 5805, 6345, 6448, 6496, 6552, 6860, 6944, 7155, 7965, 8235, 8288, 8432, 9045, 9184, 9424, 9585, 9632, 9855, 10296, 10528, 10665, 10976
Offset: 1
Keywords
Examples
135 is a term since the harmonic mean of divisors of 135 is 9/2, and it is also the harmonic mean of divisors of 84 which is smaller than 135.
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000
- Amiram Eldar, Table of n, a(n), least k for n=1..1000
Programs
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Mathematica
h = Table[DivisorSigma[0, n]/DivisorSigma[-1, n], {n, 1, 10000}]; i = Position[(t = Tally[h])[[;; , 2]], _?(# > 1 &)] // Flatten; Position[h, #][[2 ;; -1]] & /@ t[[i, 1]] // Flatten // Sort
Comments