A121602 - OEIS

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A121602

Decimal expansion of cosecant of 20 degrees = csc(Pi/9).

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

	OFFSET	`1,1`
	COMMENTS	`1 + csc(Pi/9) is the radius of the smallest circle into which 11 unit circles can be packed ("r=3.923+ Proved by Melissen in 1994.", according to the Friedman link, which has a diagram). csc(Pi/9) [=1/A019829] is the distance between the center of the larger circle and the center of each unit circle that touches the larger circle.`
	EXAMPLE	`2.9238044001630872522327544133662917...`
	PROG	`(PARI) 1/sin(Pi/9)`
	CROSSREFS	`Cf. A019829 (1/A121602), A121601.` `Sequence in context: A011065 A088540 A019826 * A011324 A021346 A010597` `Adjacent sequences: A121599 A121600 A121601 * A121603 A121604 A121605`
	KEYWORD	`cons,nonn`
	AUTHOR	`Rick L. Shepherd (rshepherd2(AT)hotmail.com), Aug 09 2006`

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Last modified February 15 12:25 EST 2012. Contains 205786 sequences.