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A218406 Numbers k for which sigma(k)/k - 1/5 is an integer. 5

%I #26 May 13 2023 20:00:49

%S 5,420,7440,8190,18600,121920,131040,95472000,102136320,197308800,

%T 433305600,503255040,71271827200,91967616000,128848035840,

%U 190066406400,287879454720,354560976000,799959888000,2061580369920,2208930048000,100368143884800,341546502528000

%N Numbers k for which sigma(k)/k - 1/5 is an integer.

%C a(15) > 10^11. - _Donovan Johnson_, Oct 31 2012

%C a(20) > 10^12. - _Giovanni Resta_, Nov 04 2012

%C Note that there are no terms here with abundancy 11/5 (k=2). - _Michel Marcus_, Jun 26 2013

%Y Cf. A218407, A218408, A218427.

%K nonn

%O 1,1

%A _Zdenek Cervenka_, Oct 28 2012

%E a(8)-a(14) from _Donovan Johnson_, Oct 31 2012

%E a(15)-a(19) from _Giovanni Resta_, Nov 04 2012

%E More terms from _Michel Marcus_, Jun 26 2013

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Last modified March 28 22:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)