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A007509 Numerator of Sum_{k=0..n} (-1)^k/(2*k+1).
(Formerly M2061)
+0
2
1, 2, 13, 76, 263, 2578, 36979, 33976, 622637, 11064338, 11757173, 255865444, 1346255081, 3852854518, 116752370597, 3473755390832, 3610501179557, 3481569435902, 133330680156299, 129049485078524, 5457995496252709 (list; graph; listen)
OFFSET

0,2

COMMENT

Denominators of convergents to 4/pi.

REFERENCES

P. Beckmann, A History of Pi. Golem Press, Boulder, CO, 2nd ed., 1971, p. 131.

LINKS

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.

EXAMPLE

[ 1 ], 2/3, 13/15, 76/105, 263/315, 2578/3465, 36979/45045, 33976/45045, 622637/765765,...

MAPLE

A007509 := n->numer(add((-1)^k/(2*k+1), k=0..n));

CROSSREFS

Denominators are A025547.

Sequence in context: A097349 A109112 A004027 this_sequence A077413 A024199 A037523

Adjacent sequences: A007506 A007507 A007508 this_sequence A007510 A007511 A007512

KEYWORD

nonn,easy,nice,frac

AUTHOR

njas

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Last modified July 4 18:25 EDT 2008. Contains 140886 sequences.


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