The OEIS is supported by the many generous donors to the OEIS Foundation.
Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.
Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.
%I #23 Sep 08 2022 08:46:04
%S 23,35,39,63,116,296,848,9536,35456,2118656,537214976,2148171776,
%T 137444458496
%N Numbers n whose deficiency is 22: sigma(n) - 2*n = -22.
%C Suggested by _N. J. A. Sloane_ and _Robert G. Wilson v_.
%C a(14) > 10^12.
%C a(14) > 10^13. - _Giovanni Resta_, Mar 29 2013
%C a(14) > 10^18. - _Hiroaki Yamanouchi_, Aug 21 2018
%C Any term x of this sequence can be combined with any term y of A223612 to satisfy the property (sigma(x)+sigma(y))/(x+y) = 2, which is a necessary (but not sufficient) condition for two numbers to be amicable. - _Timothy L. Tiffin_, Sep 13 2016
%e n = 9536. sigma(n)-2*n = -22.
%t Select[Range[1, 10^8], DivisorSigma[1, #] - 2 # == - 22 &] (* _Vincenzo Librandi_, Sep 14 2016 *)
%o (PARI) for(n=1, 10^8, if(sigma(n)-2*n==-22, print1(n ", ")))
%o (Magma) [n: n in [1..9*10^6] | (SumOfDivisors(n)-2*n) eq -22]; // _Vincenzo Librandi_, Sep 14 2016
%Y Cf. A000203, A033879, A223612 (abundance 22).
%K nonn,more
%O 1,1
%A _Donovan Johnson_, Mar 23 2013