A138500 Decimal expansion of arc length of the quadrifolium.

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, 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, 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

Offset: 1

Author

Eric W. Weisstein, Mar 20 2008

Keywords

• nonn
• cons

Comments

Also the perimeter of an ellipse with semi-axis lengths 2 and 1. - Jeremy Tan, May 31 2016

Examples

			9.6884482205476761984...
		

Links

• G. C. Greubel, Table of n, a(n) for n = 1..10000
• Eric Weisstein's World of Mathematics, Quadrifolium

Programs

Maple

evalf(8*EllipticE(sqrt(3)/2), 120); # Vaclav Kotesovec, Apr 22 2015

Mathematica

RealDigits[8 EllipticE[3/4],10,120][[1]] (* Harvey P. Dale, Jun 20 2011 *)

SageMath

numerical_approx( 8*elliptic_ec(3/4), digits=130) # G. C. Greubel, Apr 22 2024