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 A188731 #13 Sep 08 2022 08:45:56 %S A188731 2,8,5,0,7,8,1,0,5,9,3,5,8,2,1,2,1,7,1,6,2,2,0,5,4,4,1,8,6,5,5,4,5,3, %T A188731 3,1,6,1,3,0,1,0,5,0,3,3,1,5,5,2,5,4,7,2,1,3,8,2,3,1,8,1,5,6,6,6,7,0, %U A188731 4,5,6,8,9,5,4,9,2,1,9,0,1,8,5,7,2,3,3,8,5,7,5,5,6,2,4,6,7,4,9,0,7,9,2,7,0,2,9,5,8,1,2,5,9,4,9,2,9,5,8,1,5,6,1,7,4,3,6,0,9,3 %N A188731 Decimal expansion of (5+sqrt(41))/4. %C A188731 Decimal expansion of shape of a (5/2)-extension rectangle; see A188640 for definitions of shape and r-extension rectangle. Briefly, shape=length/width, and an r-extension rectangle is composed of two rectangles of shape r. %C A188731 The continued fractions of the constant are 2, 1, 5, 1, 2, 2, 1, 5, 1, 2, 2, 1, 5, 1, 2, 2, 1, 5, 1... %H A188731 G. C. Greubel, <a href="/A188731/b188731.txt">Table of n, a(n) for n = 1..10000</a> %e A188731 2.850781059358212171622054418655453316130105033155254721... %p A188731 evalf((5+sqrt(41))/4,140); # _Muniru A Asiru_, Nov 01 2018 %t A188731 r = 5/2; t = (r + (4 + r^2)^(1/2))/2; FullSimplify[t] %t A188731 N[t, 130] %t A188731 RealDigits[N[t, 130]][[1]] %t A188731 ContinuedFraction[t, 120] %o A188731 (PARI) default(realprecision, 100); (5+sqrt(41))/4 \\ _G. C. Greubel_, Nov 01 2018 %o A188731 (Magma) SetDefaultRealField(RealField(100)); (5+Sqrt(41))/4; // _G. C. Greubel_, Nov 01 2018 %Y A188731 Cf. A188640. %K A188731 nonn,cons %O A188731 1,1 %A A188731 _Clark Kimberling_, Apr 10 2011