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A067262
Numbers k such that sigma(k+1) = 4*phi(k).
3
2, 6, 14, 20, 30, 54, 104, 114, 132, 140, 234, 252, 279, 314, 434, 539, 620, 644, 798, 860, 1064, 1080, 1154, 1287, 1308, 1500, 1595, 1715, 1904, 2232, 2294, 2375, 2736, 2772, 2925, 3212, 3219, 3684, 3834, 4014, 4070, 4344, 4464, 4730, 4959, 5075, 5159
OFFSET
1,1
LINKS
MATHEMATICA
Select[Range[5000], DivisorSigma[1, #+1] == 4*EulerPhi[#] &] (* Amiram Eldar, Apr 24 2022 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Feb 21 2002
STATUS
approved