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 A190287 #4 Mar 30 2012 18:57:27
%S A190287 5,4,1,3,0,8,5,6,4,5,4,1,1,0,2,8,7,1,0,2,8,7,0,6,5,5,6,7,5,5,7,4,9,4,
%T A190287 1,3,5,3,1,5,9,3,2,7,3,6,5,0,4,1,2,5,8,4,1,5,5,0,5,1,3,3,7,5,9,2,2,6,
%U A190287 7,7,4,4,9,2,3,3,0,9,7,1,9,2,2,5,1,8,4,8,8,1,5,1,0,0,2,8,8,0,8,8,7,4,0,9,0,0,2,2,3,2,0,9,6,8,1,4,0,4,0,2
%N A190287 Decimal expansion of (5+sqrt(25+4r))/2, where r=sqrt(5).
%C A190287 The rectangle R whose shape (i.e., length/width) is (5+sqrt(25+4r))/2, where r=sqrt(5), can be partitioned into rectangles of shapes 5 and r in a manner that matches the periodic continued fraction [5, r, 5, r, ...]. R can also be partitioned into squares so as to match the nonperiodic continued fraction [5,2,2,2,1,1,1,10,1,1,2,1,...] at A190288. For details, see A188635.
%e A190287 5.413085645411028710287065567557494135316...
%t A190287 r=5^(1/2)
%t A190287 FromContinuedFraction[{5, r, {5, r}}]
%t A190287 FullSimplify[%]
%t A190287 ContinuedFraction[%, 100] (* A190288 *)
%t A190287 RealDigits[N[%%, 120]] (* A190287 *)
%t A190287 N[%%%, 40]
%Y A190287 Cf. A188635, A190288.
%K A190287 nonn,cons
%O A190287 1,1
%A A190287 _Clark Kimberling_, May 07 2011