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Search: id:A007509
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| A007509 |
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Numerator of Sum_{k=0..n} (-1)^k/(2*k+1).
(Formerly M2061)
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+0
9
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| 1, 2, 13, 76, 263, 2578, 36979, 33976, 622637, 11064338, 11757173, 255865444, 1346255081, 3852854518, 116752370597, 3473755390832, 3610501179557, 3481569435902, 133330680156299, 129049485078524, 5457995496252709
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Denominators of convergents to 4/pi.
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REFERENCES
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P. Beckmann, A History of Pi. Golem Press, Boulder, CO, 2nd ed., 1971, p. 131.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
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EXAMPLE
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[ 1 ], 2/3, 13/15, 76/105, 263/315, 2578/3465, 36979/45045, 33976/45045, 622637/765765,...
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MAPLE
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A007509 := n->numer(add((-1)^k/(2*k+1), k=0..n));
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CROSSREFS
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Denominators are A025547.
Contribution from Johannes W. Meijer (meijgia(AT)hotmail.com), Nov 12 2009: (Start)
Cf. A157142 and A166107.
Appears in A167576, A167577, A167578, A024199, A167588 and A167589.
(End)
Sequence in context: A004027 A154357 A161130 this_sequence A077413 A024199 A037523
Adjacent sequences: A007506 A007507 A007508 this_sequence A007510 A007511 A007512
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KEYWORD
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nonn,easy,nice,frac
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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