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 A231546 #20 May 28 2024 15:01:57
%S A231546 15,207,958,1335,1365,1635,2686,2975,4365,14842,18874,19359,20146,
%T A231546 24958,33999,36567,42819,56565,64666,74919,79827,79834,84135,92686,
%U A231546 109215,111507,116938,122074,138238,147455,161002,162603,166935,174718,190774,193894,201598
%N A231546 Numbers k such that sigma(k) = sigma(k-1).
%C A231546 Also, numbers k such that k = antisigma(k) - antisigma(k-1), where antisigma(k) = A024816(k) = the sum of the non-divisors of k that are between 1 and k.
%H A231546 Amiram Eldar, <a href="/A231546/b231546.txt">Table of n, a(n) for n = 1..10135</a> (calculated using the b-file at A002961; terms 1..550 from Hugo Pfoertner)
%F A231546 a(n) = A002961(n) + 1.
%e A231546 15 = antisigma(15) - antisigma(14) = 96 - 81.
%t A231546 SequencePosition[DivisorSigma[1,Range[210000]],{x_,x_}][[;;,2]] (* _Harvey P. Dale_, May 28 2024 *)
%o A231546 (PARI) n=0;sp=sigma(2);for(k=3,oo,my(s=sigma(k));if(s==sp,print1(k,", ");n++;if(n>36,break));sp=s) \\ _Hugo Pfoertner_, Mar 06 2020
%Y A231546 Cf. A002961, A024816 (antisigma(n)), A231545 (numbers n such that antisigma(n) = antisigma(n-1)).
%K A231546 nonn
%O A231546 1,1
%A A231546 _Jaroslav Krizek_, Nov 11 2013
%E A231546 More terms from _Hugo Pfoertner_, Mar 06 2020