A051346 Numbers that can be written as k/d(k) in four or more ways, where d(k) = number of divisors of k.

11264, 14175, 28160, 44100, 46464, 51200, 64000, 82944, 95744, 96000, 107008, 109375, 109760, 116160, 129536, 151263, 162624, 163328, 174592, 192000, 208384, 224000, 230912, 239360, 242176, 242550, 246960, 264704, 267520, 281600, 286650, 290304, 298496, 302016

Offset

1,1

Links

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

Example

From Jon E. Schoenfield, Feb 18 2021: (Start)
11264 is a term because it can be written as k/d(k) in four ways:
k =  360448:  360448/d(360448)  =  360448/32 = 11264;
k =  585728:  585728/d(585728)  =  585728/52 = 11264;
k =  630784:  630784/d(630784)  =  630784/56 = 11264;
k = 1115136: 1115136/d(1115136) = 1115136/99 = 11264. (End)

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[310000], cnt[#] >= 4 &] (* Jean-François Alcover, Sep 28 2012 *)

Crossrefs

Cf. A000005, A051278, A051279, A051280, A217125, A217126, A217127.

Sequence in context: A031630 A064870 A051520 * A217125 A195654 A195649

Adjacent sequences: A051343 A051344 A051345 * A051347 A051348 A051349

Keyword

nonn

Author

David W. Wilson

Status

approved