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 A348689 #12 Oct 30 2021 11:43:57
%S A348689 0,0,5,1,10,5,10,10,19,2,26,18,14,17,37,10,37,17,30,38,44,0,53,49,33,
%T A348689 26,66,14,70,41,47,57,54,11,101,69,42,26,104,36,94,56,50,90,102,-4,
%U A348689 115,88,78,67,116,32,102,72,112,110,110,-18,166,134,54,73,147,67,160,86,98,78,168,21
%N A348689 a(n) = sigma(n) + sigma(n+1) - sigma(n+2), where sigma is the sum of divisors.
%H A348689 Michel Marcus, <a href="/A348689/b348689.txt">Table of n, a(n) for n = 1..10000</a>
%t A348689 Array[#+#2-#3&@@DivisorSigma[1,{#,#+1,#+2}]&,100] (* _Giorgos Kalogeropoulos_, Oct 29 2021 *)
%o A348689 (PARI) a(n) = sigma(n)+sigma(n+1) - sigma(n+2);
%Y A348689 Cf. A000203, A104149, A348688.
%K A348689 sign
%O A348689 1,3
%A A348689 _Michel Marcus_, Oct 29 2021