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 A010476 #29 Aug 21 2023 10:33:58
%S A010476 4,4,7,2,1,3,5,9,5,4,9,9,9,5,7,9,3,9,2,8,1,8,3,4,7,3,3,7,4,6,2,5,5,2,
%T A010476 4,7,0,8,8,1,2,3,6,7,1,9,2,2,3,0,5,1,4,4,8,5,4,1,7,9,4,4,9,0,8,2,1,0,
%U A010476 4,1,8,5,1,2,7,5,6,0,9,7,9,8,8,2,8,8,2,8,8,1,6,7,5,7,5,6,4,5,4,9,9,3,9,0,1
%N A010476 Decimal expansion of square root of 20.
%C A010476 Continued fraction expansion is 4 followed by {2, 8} repeated. - _Harry J. Smith_, Jun 03 2009
%H A010476 Harry J. Smith, <a href="/A010476/b010476.txt">Table of n, a(n) for n = 1..20000</a>
%H A010476 <a href="/index/Al#algebraic_02">Index entries for algebraic numbers, degree 2</a>
%F A010476 sqrt(20) = 2*sqrt(5). - _Alonso del Arte_, Jun 26 2015
%F A010476 Equals Sum_{k>=0} binomial(2*k,k) * k/5^k. - _Amiram Eldar_, Aug 03 2020
%e A010476 4.472135954999579392818347337462552470881236719223051448541794490821041....
%t A010476 RealDigits[N[Sqrt[20], 100]][[1]] (* _Vladimir Joseph Stephan Orlovsky_, Feb 21 2011 *)
%o A010476 (PARI) default(realprecision, 20080); x=sqrt(20); for (n=1, 20000, d=floor(x); x=(x-d)*10; write("b010476.txt", n, " ", d)); \\ _Harry J. Smith_, Jun 03 2009
%Y A010476 Except for offset, same as A020762.
%Y A010476 Cf. A040015 (continued fraction). - _Harry J. Smith_, Jun 03 2009
%Y A010476 Cf. A002163 (decimal expansion of square root of 5).
%K A010476 nonn,cons,easy
%O A010476 1,1
%A A010476 _N. J. A. Sloane_