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A122216 Numerators in infinite products for Pi/2, e and e^gamma (unreduced). +0
6
1, 2, 4, 32, 4096, 201326592, 3283124128353091584, 26520146032764463901929624736590416838656, 8409872218845584878346591802015832570333859884111674529900728420499238460920 (list; graph; listen)
OFFSET

1,2

REFERENCES

J. Sondow, A faster product for Pi and a new integral for ln Pi/2, Amer. Math. Monthly 112 (2005) 729-734.

LINKS

J. Baez, This Week's Finds in Mathematical Physics

J. Guillera and J. Sondow, Double integrals and infinite products for some classical constants via analytic continuations of Lerch's transcendent

FORMULA

a(n) = product(k = 1...ceiling(n/2), (2k)^binomial(n,2k-1)).

EXAMPLE

Pi/2 = (2/1)^(1/2) * (4/3)^(1/4) * (32/27)^(1/8) *

(4096/3645)^(1/16) * ...,

e = (2/1)^(1/1) * (4/3)^(1/2) * (32/27)^(1/3) * (4096/3645)^(1/4) * ... and

e^gamma = (2/1)^(1/2) * (4/3)^(1/3) * (32/27)^(1/4) * (4096/3645)^(1/5) *

....

CROSSREFS

Cf. A092798. Denominators are A122217. Reduced numerators are A122214.

Sequence in context: A118992 A062740 A122214 this_sequence A100117 A073888 A114642

Adjacent sequences: A122213 A122214 A122215 this_sequence A122217 A122218 A122219

KEYWORD

frac,nonn

AUTHOR

Jonathan Sondow (jsondow(AT)alumni.princeton.edu), Aug 26 2006

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Last modified November 23 17:09 EST 2009. Contains 167438 sequences.


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