A093728 Decimal expansion of 2E(2i sqrt(2)), where E(k) is the complete elliptic integral of the 2nd kind.

6, 6, 8, 2, 4, 4, 6, 6, 1, 0, 2, 7, 7, 6, 2, 9, 1, 1, 5, 0, 6, 4, 7, 5, 1, 1, 6, 2, 5, 3, 0, 0, 9, 8, 1, 1, 9, 7, 0, 0, 4, 9, 1, 3, 3, 6, 1, 9, 4, 5, 8, 8, 5, 5, 1, 6, 4, 6, 4, 8, 0, 1, 9, 8, 2, 4, 6, 2, 9, 2, 7, 0, 9, 5, 2, 3, 2, 8, 4, 8, 0, 4, 0, 1, 2, 9, 5, 5, 3, 2, 4, 0, 5, 8, 1, 9, 9, 1, 0, 6, 4, 5

Offset

1,1

Comments

Arc length of the trifolium r = a*cos(3*theta).

Links

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

Eric Weisstein's World of Mathematics, Trifolium

Formula

Equals 2*A249491. - Altug Alkan, Oct 02 2018

Example

6.68244661027762911506475116253009811970049133619458855164648...

Maple

Re(evalf(2*EllipticE(2*I*sqrt(2)), 120)); # Vaclav Kotesovec, Apr 22 2015

Mathematica

RealDigits[ N[ 2*EllipticE[-8], 102]][[1]] (* Jean-François Alcover, Oct 29 2012 *)

Prog

(PARI) 2*intnum(t=0, Pi/2, sqrt(1+8*sin(t)^2)) \\ Charles R Greathouse IV, Aug 15 2015

Crossrefs

Cf. A249491.

Sequence in context: A279005 A198987 A198751 * A324001 A205863 A132711

Adjacent sequences: A093725 A093726 A093727 * A093729 A093730 A093731

Keyword

nonn,cons

Author

Eric W. Weisstein, Apr 13 2004

Status

approved