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 A040021 #34 Aug 25 2025 11:09:27
%S A040021 5,5,10,5,10,5,10,5,10,5,10,5,10,5,10,5,10,5,10,5,10,5,10,5,10,5,10,5,
%T A040021 10,5,10,5,10,5,10,5,10,5,10,5,10,5,10,5,10,5,10,5,10,5,10,5,10,5,10,
%U A040021 5,10,5,10,5,10,5,10,5,10,5
%N A040021 Continued fraction for sqrt(27).
%D A040021 James J. Tattersall, Elementary Number Theory in Nine Chapters, Cambridge University Press, 1999, page 276.
%H A040021 Harry J. Smith, <a href="/A040021/b040021.txt">Table of n, a(n) for n = 0..20000</a>
%H A040021 G. Xiao, <a href="http://wims.unice.fr/~wims/en_tool~number~contfrac.en.html">Contfrac</a>
%H A040021 <a href="/index/Con#confC">Index entries for continued fractions for constants</a>
%H A040021 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (0,1).
%F A040021 G.f.: 5*(1 + x + x^2)/(1 - x^2). - _Stefano Spezia_, Jul 26 2025
%e A040021 5.1961524227066318805823390... = 5 + 1/(5 + 1/(10 + 1/(5 + 1/(10 + ...)))). - _Harry J. Smith_, Jun 04 2009
%p A040021 Digits := 100: convert(evalf(sqrt(N)),confrac,90,'cvgts'):
%t A040021 ContinuedFraction[Sqrt[27],300] (* _Vladimir Joseph Stephan Orlovsky_, Mar 05 2011 *)
%t A040021 PadRight[{5},120,{10,5}] (* _Harvey P. Dale_, Jul 19 2015 *)
%o A040021 (PARI) { allocatemem(932245000); default(realprecision, 35000); x=contfrac(sqrt(27)); for (n=0, 20000, write("b040021.txt", n, " ", x[n+1])); } \\ _Harry J. Smith_, Jun 04 2009
%o A040021 (Magma) ContinuedFraction(Sqrt(27)); // _G. C. Greubel_, Feb 16 2018
%Y A040021 Cf. A010482 (Decimal expansion), A010721.
%K A040021 nonn,cofr,easy,changed
%O A040021 0,1
%A A040021 _N. J. A. Sloane_