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Search: id:A121601
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| A121601 |
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Decimal expansion of cosecant of 22.5 degrees = csc(Pi/8). |
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+0
4
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| 2, 6, 1, 3, 1, 2, 5, 9, 2, 9, 7, 5, 2, 7, 5, 3, 0, 5, 5, 7, 1, 3, 2, 8, 6, 3, 4, 6, 8, 5, 4, 3, 7, 4, 3, 0, 7, 1, 6, 7, 5, 2, 2, 3, 7, 6, 6, 9, 8, 5, 3, 9, 0, 5, 5, 0, 9, 7, 7, 9, 6, 7, 3, 3, 8, 1, 6, 1, 6, 2, 0, 8, 2, 9, 2, 2, 3, 8, 4, 1, 0, 1, 9, 0, 3, 7, 0, 7, 4, 4, 0, 3, 8, 5, 2, 5, 6, 2, 8, 6, 4, 9, 2, 7, 7
(list; cons; graph; listen)
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OFFSET
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1,1
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COMMENT
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Also, decimal expansion of 2*sqrt(2)*cos(Pi/8).
1 + csc(Pi/8) is the radius of the smallest circle into which 9 unit circles can be packed ("r=3.613+ Proved by Pirl in 1969.", according to the Friedman link, which has a diagram). csc(Pi/8) is the distance between the center of the larger circle and the center of each unit circle that touches the larger circle.
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REFERENCES
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D. Mumford et al., Indra's Pearls, Cambridge 2002; see p. 362. [From N. J. A. Sloane, Nov 22 2009]
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EXAMPLE
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2.6131259297527530557132863468543743071675223766985390550977...
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PROGRAM
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(PARI) 1/sin(Pi/8)
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CROSSREFS
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Cf. A121598.
Sequence in context: A024573 A078434 A021892 this_sequence A122761 A100469 A124320
Adjacent sequences: A121598 A121599 A121600 this_sequence A121602 A121603 A121604
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KEYWORD
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cons,nonn,new
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AUTHOR
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Rick L. Shepherd (rshepherd2(AT)hotmail.com), Aug 09 2006
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