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
KEYWORD
nonn
AUTHOR
Donovan Johnson, Sep 27 2012
STATUS
approved