

A121598


Decimal expansion of cosecant of 180/7 = 25.7142857+ degrees = csc(Pi/7).


4



2, 3, 0, 4, 7, 6, 4, 8, 7, 0, 9, 6, 2, 4, 8, 6, 5, 0, 5, 2, 4, 1, 1, 5, 0, 2, 2, 3, 5, 4, 6, 8, 5, 5, 1, 1, 3, 4, 4, 4, 5, 0, 1, 8, 8, 7, 6, 0, 6, 3, 2, 1, 1, 6, 2, 0, 6, 3, 1, 0, 6, 2, 9, 6, 4, 6, 6, 8, 5, 3, 3, 4, 2, 7, 7, 8, 4, 7, 9, 5, 9, 6, 3, 7, 9, 1, 1, 1, 4, 2, 1, 9, 7, 4, 7, 6, 1, 7, 9, 3, 6, 1, 5, 1, 5
(list;
constant;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,1


COMMENTS

1 + csc(Pi/7) is the radius of the smallest circle into which 8 unit circles can be packed ("r=3.304+ Proved by Braaksma in 1963.", according to the Friedman link, which has a diagram).
csc(Pi/7) is the distance between the center of the larger circle and the center of each unit circle that touches the larger circle.


LINKS

G. C. Greubel, Table of n, a(n) for n = 1..10000
E. Friedman, Erich's Packing Center: "Circles in Circles"


EXAMPLE

2.304764870962486505241150223546855...


MATHEMATICA

RealDigits[Csc[Pi/7], 10, 100][[1]] (* G. C. Greubel, Nov 02 2018 *)


PROG

(PARI) 1/sin(Pi/7)
(MAGMA) SetDefaultRealField(RealField(100)); R:= RealField(); 1/Sin(Pi(R)/7); // G. C. Greubel, Nov 02 2018


CROSSREFS

Cf. A121570.
Sequence in context: A286578 A010340 A049275 * A258818 A261275 A140326
Adjacent sequences: A121595 A121596 A121597 * A121599 A121600 A121601


KEYWORD

cons,nonn


AUTHOR

Rick L. Shepherd, Aug 09 2006


STATUS

approved



