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 A126333 #6 Nov 08 2017 19:31:59 %S A126333 1,2,3,5,13,65533 %N A126333 Ackermann's function A(n,0). %H A126333 R. G. Wilson v, <a href="/A126333/a126333.pdf">Letter to N. J. A. Sloane, Nov. 1988</a> %F A126333 A(0,n)=1+n, A(m+1,0)=A(m,1), A(m+1;n+1)=A(m,A(m+1,n)). %Y A126333 Cf. A014221, A001695. %K A126333 nonn %O A126333 0,2 %A A126333 Philippe LALLOUET (philip.lallouet(AT)wanadoo.fr), Mar 10 2007