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 A015883 #29 Feb 10 2024 11:36:11 %S A015883 182,782,1965,2486,2678,2685,12141,12441,17342,21242,27686,34905, %T A015883 35505,35853,38662,38985,56732,63578,104342,109461,192933,198909, %U A015883 222122,236966,245349,251654,256322,261885,262238,324441,333909 %N A015883 Numbers k such that sigma(k) = sigma(k+13). %D A015883 J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 182, p. 56, Ellipses, Paris 2008. %H A015883 Donovan Johnson, <a href="/A015883/b015883.txt">Table of n, a(n) for n = 1..1000</a> %t A015883 Select[Range[350000], DivisorSigma[1, #]==DivisorSigma[1, # + 13] &] (* _Vincenzo Librandi_, Mar 10 2014 *) %o A015883 (PARI) is(n)=sigma(n)==sigma(n+13) \\ _Charles R Greathouse IV_, Mar 09 2014 %Y A015883 Cf. A002961, A007373, A015861, A015863, A015865, A015866, A015867, A015876, A015877, A015880, A015881, A015882, A181647. %K A015883 nonn %O A015883 1,1 %A A015883 _Robert G. Wilson v_ %E A015883 Corrected by _T. D. Noe_, Oct 31 2006