%I A040015
%S A040015 4,2,8,2,8,2,8,2,8,2,8,2,8,2,8,2,8,2,8,2,8,2,8,2,8,2,8,
%T A040015 2,8,2,8,2,8,2,8,2,8,2,8,2,8,2,8,2,8,2,8,2,8,2,8,2,8,2,
%U A040015 8,2,8,2,8,2,8,2,8,2,8,2,8,2,8,2,8,2,8,2,8,2,8,2,8,2,8
%N A040015 Continued fraction for sqrt(20).
%H A040015 Harry J. Smith, <a href="b040015.txt">Table of n, a(n) for n=0,...,20000</
               a>
%H A040015 G. Xiao, <a href="http://wims.unice.fr/~wims/en_tool~number~contfrac.en.html">
               Contfrac</a>
%H A040015 <a href="Sindx_Con.html#confC">Index entries for continued fractions 
               for constants</a>
%F A040015 a(n)=5+3*(-1)^n-4*[C(2*n,n) mod 2], with n>=0 [From Paolo P. Lava (ppl(AT)spl.at), 
               Jun 11 2009]
%e A040015 4.472135954999579392818347337... = 4 + 1/(2 + 1/(8 + 1/(2 + 1/(8 + ...)))) 
               [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Jun 03 2009]
%p A040015 Digits := 100: convert(evalf(sqrt(N)),confrac,90,'cvgts'):
%o A040015 (PARI) { allocatemem(932245000); default(realprecision, 26000); x=contfrac(sqrt(20)); 
               for (n=0, 20000, write("b040015.txt", n, " ", x[n+1])); } [From Harry 
               J. Smith (hjsmithh(AT)sbcglobal.net), Jun 03 2009]
%Y A040015 Cf. A010476 Decimal expansion. [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), 
               Jun 03 2009]
%Y A040015 Sequence in context: A112152 A083489 A065464 this_sequence A144926 A153016 
               A088610
%Y A040015 Adjacent sequences: A040012 A040013 A040014 this_sequence A040016 A040017 
               A040018
%K A040015 nonn,cofr,easy
%O A040015 0,1
%A A040015 N. J. A. Sloane (njas(AT)research.att.com).