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 A138500 #22 Feb 16 2025 08:33:07 %S A138500 9,6,8,8,4,4,8,2,2,0,5,4,7,6,7,6,1,9,8,4,2,8,5,0,3,1,9,6,3,9,1,8,2,9, %T A138500 4,1,1,9,5,3,9,1,8,3,9,7,8,8,6,6,0,0,8,2,5,0,8,3,1,1,6,3,5,2,4,6,2,1, %U A138500 2,0,6,4,5,9,6,2,5,5,2,1,4,8,2,9,3,4,0,0,9,4,7,4,3,3,5,8,3,9,1,8,4,9,7,9,8 %N A138500 Decimal expansion of arc length of the quadrifolium. %C A138500 Also the perimeter of an ellipse with semi-axis lengths 2 and 1. - _Jeremy Tan_, May 31 2016 %H A138500 G. C. Greubel, <a href="/A138500/b138500.txt">Table of n, a(n) for n = 1..10000</a> %H A138500 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Quadrifolium.html">Quadrifolium</a> %e A138500 9.6884482205476761984... %p A138500 evalf(8*EllipticE(sqrt(3)/2), 120); # _Vaclav Kotesovec_, Apr 22 2015 %t A138500 RealDigits[8 EllipticE[3/4],10,120][[1]] (* _Harvey P. Dale_, Jun 20 2011 *) %o A138500 (SageMath) numerical_approx( 8*elliptic_ec(3/4), digits=130) # _G. C. Greubel_, Apr 22 2024 %K A138500 nonn,cons %O A138500 1,1 %A A138500 _Eric W. Weisstein_, Mar 20 2008