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

1,1

Links

Donovan Johnson, Table of n, a(n) for n = 1..1000

Example

k/d(k) = 11264 for exactly 4 k values: 360448, 585728, 630784 and 1115136.

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 *)

Crossrefs

Cf. A051278, A051279, A051280, A051346, A217126, A217127.

Sequence in context: A064870 A051520 A051346 * A195654 A195649 A110375

Adjacent sequences: A217122 A217123 A217124 * A217126 A217127 A217128

Keyword

nonn

Author

Donovan Johnson, Sep 27 2012

Status

approved