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 A006269 M4028 #20 Jul 08 2025 16:44:58
%S A006269 5,140,2744420,20670535451567121260,
%T A006269 8831921094058107711185956797335984862612406515067837739780
%N A006269 A continued cotangent.
%D A006269 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A006269 Jeffrey Shallit, <a href="http://archive.org/details/jresv80Bn2p285">Predictable regular continued cotangent expansions</a>, J. Res. Nat. Bur. Standards Sect. B 80B (1976), no. 2, 285-290.
%F A006269 From _Artur Jasinski_, Oct 03 2008: (Start)
%F A006269 Recurrence: a(n+1)=a(n)^3+3*a(n) and a(0)=5.
%F A006269 a(n) = round((5/2 + sqrt(29)/2)^(3^(n - 1))). (End)
%t A006269 a = {}; k = 5; Do[AppendTo[a, k]; k = k^3 + 3 k, {n, 1, 8}]; a (* _Artur Jasinski_, Oct 03 2008 *)
%t A006269 Table[Round[(5/2 + Sqrt[29]/2)^(3^(n - 1))], {n, 1, 8}] (* _Artur Jasinski_, Oct 03 2008 *)
%t A006269 NestList[#^3+3#&,5,5] (* _Harvey P. Dale_, Feb 14 2013 *)
%K A006269 nonn
%O A006269 0,1
%A A006269 _N. J. A. Sloane_