id:A001901 - OEIS Search Results

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A001901

Successive numerators of Wallis's approximation to pi/2 (reduced).

+0
4

1, 2, 4, 16, 64, 128, 256, 2048, 16384, 32768, 65536, 262144, 1048576, 2097152, 4194304, 67108864, 1073741824, 2147483648, 4294967296, 17179869184, 68719476736, 137438953472, 274877906944, 2199023255552 (list; graph; listen)

	OFFSET	`0,2`
	REFERENCES	`H.-D. Ebbinghaus et al., Numbers, Springer, 1990, p. 146.`
	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.` `J. Sondow, A faster product for Pi and a new integral for ln(Pi/2)`
	FORMULA	`... 2.2.4.4.6.6....2n.2n/1.3.3.5.5.7.7....(2n-1).(2n+1) ...`
	CROSSREFS	`Cf. A001902.` `Cf. A001902 for the denominators.` `Sequence in context: A138867 A138868 A138871 this_sequence A127588 A092585 A106186` `Adjacent sequences: A001898 A001899 A001900 this_sequence A001902 A001903 A001904`
	KEYWORD	`nonn,frac`
	AUTHOR	`njas`

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Last modified July 26 13:41 EDT 2008. Contains 142293 sequences.

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