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A067263
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Numbers k such that sigma(k+1) = 5*phi(k).
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2
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2184, 6930, 7020, 7644, 17640, 18564, 23660, 25200, 27404, 71280, 83720, 120834, 129150, 179010, 189630, 191100, 198015, 224664, 228780, 273504, 285480, 302280, 304290, 322335, 328320, 335664, 437580, 443079, 449904, 451044, 462644, 478400, 483735, 619190, 627759
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OFFSET
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1,1
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LINKS
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MATHEMATICA
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Select[Range[7*10^5], DivisorSigma[1, #+1] == 5*EulerPhi[#] &] (* Amiram Eldar, Apr 24 2022 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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