cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A223613 Numbers k whose abundance is 24: sigma(k) - 2*k = 24.

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%I A223613 #32 Jun 06 2025 06:56:46
%S A223613 112,6592,124672,33452032,82364907508,36893488040044920832,
%T A223613 9444732964021303508992
%N A223613 Numbers k whose abundance is 24: sigma(k) - 2*k = 24.
%C A223613 Suggested by _N. J. A. Sloane_ and _Robert G. Wilson v_.
%C A223613 Every number of the form 2^(j-1)*(2^j - 25), where 2^j - 25 is prime, is a term (cf. A379020). - _Jon E. Schoenfield_, Jun 02 2019
%C A223613 Also contains 269113900901410149234393088. - _Max Alekseyev_, May 28 2025
%e A223613 For k = 82364907508, sigma(k) - 2*k = 24.
%o A223613 (PARI) for(n=1, 10^8, if(sigma(n)-2*n==24, print1(n ", ")))
%Y A223613 Cf. A000203, A033880, A379020.
%K A223613 nonn,hard,more
%O A223613 1,1
%A A223613 _Donovan Johnson_, Mar 23 2013
%E A223613 a(6) from _Jon E. Schoenfield_ confirmed and a(7) added by _Max Alekseyev_, Jun 06 2025