A217125 Numbers n such that n = k/d(k) has exactly 4 solutions, where d(k) = number of divisors of k.
11264, 14175, 28160, 44100, 46464, 51200, 95744, 96000, 107008, 109375, 109760, 116160, 129536, 151263, 162624, 163328, 174592, 192000, 208384, 224000, 230912, 239360, 242176, 242550, 246960, 264704, 267520, 281600, 286650, 298496, 302016, 323840, 332288
Offset: 1
Keywords
Examples
k/d(k) = 11264 for exactly 4 k values: 360448, 585728, 630784 and 1115136.
Links
- Donovan Johnson, Table of n, a(n) for n = 1..1000
Programs
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Mathematica
(* Assuming 3*10^5 <= k <= 3*10^8 *) ClearAll[cnt]; cnt[] = 0; Do[ If[IntegerQ[n = k/DivisorSigma[0, k]], cnt[n]++; If[cnt[n] >= 4, Print[{n, k, cnt[n]}]]], {k, 3*10^5, 3*10^8}]; Select[Range[350000], cnt[#] == 4 &] (* _Jean-François Alcover, Sep 28 2012 *)