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 A240824 #12 Jul 16 2015 23:02:57
%S A240824 21,72,35,0,47,35,37,40,91,0,143,71,92
%N A240824 a(n) = index of first nonexisting term of the meta-Fibonacci sequence {f(k) = k for k <= n; f(k)=f(k-f(k-3))+f(k-f(k-n))} if that sequence is only defined for finitely many terms, or 0 if that sequence is infinite.
%C A240824 a(6)=0 and a(12)=0 are only conjectures.
%C A240824 Except for the zero entries, this is equal to A240820(n)+1. See that entry for further information.
%D A240824 D. R. Hofstadter, Curious patterns and non-patterns in a family of meta-Fibonacci recursions, Lecture in Doron Zeilberger's Experimental Mathematics Seminar, Rutgers University, April 10 2014.
%H A240824 D. R. Hofstadter, Curious patterns and non-patterns in a family of meta-Fibonacci recursions, Lecture in Doron Zeilberger's Experimental Mathematics Seminar, Rutgers University, April 10 2014; <a href="https://vimeo.com/91708646">Part 1</a>, <a href="https://vimeo.com/91710600">Part 2</a>.
%H A240824 <a href="/index/Ho#Hofstadter">Index entries for Hofstadter-type sequences</a>
%Y A240824 See A240820 for another version.
%Y A240824 A diagonal of the triangle in A240825.
%K A240824 nonn,more
%O A240824 3,1
%A A240824 _N. J. A. Sloane_, Apr 15 2014