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 A087814 #4 Mar 30 2012 17:34:13
%S A087814 1,1,13,15,25,39,47,51,69,81,101,139,249,261,275,291,739,1243,2243
%N A087814 Sequence gives A087655(n) for those n such that A087655(n) = A087655(n+1).
%t A087814 Hofstadter123[n_Integer?Positive] := Hofstadter123[n] = Hofstadter123[Abs[n - Hofstadter123[n-1]]] + Hofstadter123[Abs[n - Hofstadter123[n-2]]]+ Hofstadter123[Abs[n - Hofstadter123[n-3]]] Hofstadter123[0] =Hofstadter123[1] = Hofstadter123[2]= Hofstadter123[3]= 1 digits=30000 ta=Table[Hofstadter123[n], {n, 1, digits}]; b=Table[If[ta[[n]]-ta[[n-1]]==0, ta[[n]], 0], {n, 2, digits}]; c=Delete[Union[b], 1]
%Y A087814 Cf. A087655.
%K A087814 nonn
%O A087814 0,3
%A A087814 _Roger L. Bagula_, Oct 05 2003