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A122217 Denominators in infinite products for Pi/2, e and e^gamma (unreduced). +0
6
1, 1, 3, 27, 3645, 184528125, 3065257232666015625, 25071642180724968784488737583160400390625, 80220075338110866905430754850505863041381217435482620103925910370890051126480102\ 5390625 (list; graph; listen)
OFFSET

0,3

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...floor(n/2)+1, (2k-1)^binomial(n,2k-2)).

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) *

...

MATHEMATICA

Table[Product[(2k-1)^Binomial[n, 2k-2], {k, 1+Floor[n/2]}], {n, 0, 8}] - T. D. Noe (noe(AT)sspectra.com), Nov 16 2006

CROSSREFS

Cf. A092799. Numerators are A122216. Reduced denominators are A122215.

Sequence in context: A009039 A137092 A122215 this_sequence A068221 A068222 A055777

Adjacent sequences: A122214 A122215 A122216 this_sequence A122218 A122219 A122220

KEYWORD

frac,nonn

AUTHOR

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

EXTENSIONS

Corrected by T. D. Noe (noe(AT)sspectra.com), Nov 16 2006

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


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