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 A217704 #23 Feb 25 2018 20:45:59
%S A217704 34,53,23,19,26,41,31,38,49,52,68,82,112,80,103,76,110,123,166,83,101,
%T A217704 136,219,164,130,186,147,133,381,254,208,149,253,169,131,246,172,332,
%U A217704 404,166,245,312,148,209,309,241,487,328,217,260
%N A217704 Smallest number k > n for which sigma(k-n) = sigma(k+n).
%C A217704 The sigma() in the definition is the sum-of-divisors function A000203.
%H A217704 Andrew Howroyd, <a href="/A217704/b217704.txt">Table of n, a(n) for n = 1..10000</a>
%e A217704 a(26)=186 because sigma(186-26)=sigma(160)=378=sigma(212)=sigma(186+26) and there is no k such that 26<k<186 for which sigma(k-26)=sigma(k+26).
%t A217704 Table[Min[Select[Range[500],DivisorSigma[1, # - n] == DivisorSigma[1, # + n] && # > n &]], {n,50}]
%o A217704 (PARI) a(n)={my(k=n+1); while(sigma(k-n)<>sigma(k+n), k++); k} \\ _Andrew Howroyd_, Feb 25 2018
%Y A217704 Cf. A217768.
%K A217704 nonn
%O A217704 1,1
%A A217704 _Jayanta Basu_, Mar 26 2013