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.
%I A088832 #41 Aug 09 2025 19:31:19
%S A088832 12,70,88,1888,4030,5830,32128,521728,1848964,8378368,34359083008,
%T A088832 66072609790,549753192448,259708613909470,2251799645913088,
%U A088832 9223372026117357568
%N A088832 Numbers k whose abundance is 4: sigma(k) - 2*k = 4.
%C A088832 If 2^m-5 is prime (A059608) then n=2^(m-1)*(2^m-5) is in the sequence. 12, 88, 1888, 32128, 521728, 8378368 & 34359083008 are such terms. See comments in A088831. - _Farideh Firoozbakht_, Feb 15 2008
%C A088832 Any term x of this sequence can be combined with any term y of A125246 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
%C A088832 Also contains 865268370658615254581248 = 2^23 * 16823249 * 6131278669. - _Max Alekseyev_, May 29 2025
%F A088832 Solutions to sigma(x)-2*x=4.
%e A088832 Abundances of terms in A045769: {-5,4,4,4,4,4,4,4,4,4} so A045769(1)=9 is not here.
%t A088832 Do[If[DivisorSigma[1,n]==2n+4,Print[n]],{n,650000000}] (* _Farideh Firoozbakht_, Feb 15 2008 *)
%o A088832 (PARI) is(n)=sigma(n)==2*n+4 \\ _Charles R Greathouse IV_, Feb 21 2017
%Y A088832 Subsequence of A045769.
%Y A088832 Cf. A033880, A045768, A088830, A059608, A125246 (deficiency 4).
%K A088832 nonn,more
%O A088832 1,1
%A A088832 _Labos Elemer_, Oct 28 2003
%E A088832 One more terms from _Farideh Firoozbakht_, Feb 15 2008
%E A088832 a(11)-a(12) from _Donovan Johnson_, Dec 23 2008
%E A088832 a(13) from _Donovan Johnson_, Dec 08 2011
%E A088832 a(14)-a(15) from _Hiroaki Yamanouchi_, Aug 23 2018
%E A088832 a(16) from _Max Alekseyev_, May 29 2025