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 A040035 #27 Jul 27 2025 10:05:01
%S A040035 6,2,12,2,12,2,12,2,12,2,12,2,12,2,12,2,12,2,12,2,12,2,12,2,12,2,12,2,
%T A040035 12,2,12,2,12,2,12,2,12,2,12,2,12,2,12,2,12,2,12,2,12,2,12,2,12,2,12,
%U A040035 2,12,2,12,2,12,2,12,2,12,2
%N A040035 Continued fraction for sqrt(42).
%D A040035 James J. Tattersall, Elementary Number Theory in Nine Chapters, Cambridge University Press, 1999, page 276.
%H A040035 Harry J. Smith, <a href="/A040035/b040035.txt">Table of n, a(n) for n = 0..20000</a>
%H A040035 G. Xiao, <a href="http://wims.unice.fr/~wims/en_tool~number~contfrac.en.html">Contfrac</a>
%H A040035 <a href="/index/Con#confC">Index entries for continued fractions for constants</a>
%H A040035 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (0, 1).
%F A040035 From _Stefano Spezia_, Jul 27 2025: (Start)
%F A040035 a(n) = 2*A040011(n).
%F A040035 G.f.: 2*(3 + x + 3*x^2)/(1 - x^2). (End)
%e A040035 6.4807406984078602309659674... = 6 + 1/(2 + 1/(12 + 1/(2 + 1/(12 + ...)))). - _Harry J. Smith_, Jun 05 2009
%p A040035 Digits := 100: convert(evalf(sqrt(N)),confrac,90,'cvgts'):
%t A040035 ContinuedFraction[Sqrt[42],300] (* _Vladimir Joseph Stephan Orlovsky_, Mar 06 2011 *)
%o A040035 (PARI) { allocatemem(932245000); default(realprecision, 29000); x=contfrac(sqrt(42)); for (n=0, 20000, write("b040035.txt", n, " ", x[n+1])); } \\ _Harry J. Smith_, Jun 05 2009
%Y A040035 Cf. A010496 (decimal expansion), A040011.
%K A040035 nonn,cofr,easy
%O A040035 0,1
%A A040035 _N. J. A. Sloane_