A138500 - OEIS

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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

(list; constant; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

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

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..10000

Eric Weisstein's World of Mathematics, Quadrifolium

EXAMPLE

9.6884482205476761984...

MAPLE

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