OFFSET
1,2
COMMENTS
Since d(m) < 2*sqrt(m) < 2*sigma(m), we need only test values of m < (2*sigma(n)/d(n))^2.
LINKS
Donovan Johnson, Table of n, a(n) for n = 1..300
MATHEMATICA
crowded[n_] := Module[{}, stop=(2/(dovern=DivisorSigma[0, n]/DivisorSigma[1, n]))^2; For[m=n+1, m<stop, m++, If[DivisorSigma[0, m]/DivisorSigma[1, m] >=dovern, Return[False]]]; True]; Select[Range[1, 13000], crowded]
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Jan 09 2002
STATUS
approved