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Γ2 (½)is more than just π

Published online by Cambridge University Press:  23 January 2015

Samuel G. Moreno
Affiliation:
Departamento de Matemáticas, Universidad de Jaén, 23071 Jaén, Spain
Esther M. García-Caballero
Affiliation:
Departamento de Matemáticas, Universidad de Jaén, 23071 Jaén, Spain

Extract

For a fixed positive integer m, factorial m is defined by

The problem of finding a formula extending the factorial m! to positive real values of m was posed by D. Bernoulli and C. Goldbach and solved by Euler. In his letter of 13 October 1729 to Goldbach [1], Euler defined a function (which we denote as Γ (x + 1)) by means of

and showed that Γ (m + 1) = m! for positive integers m. After that, Euler found representations for the so-called gamma function (1) in terms of either an infinite product or an improper integral. We refer the reader to the classical (and short) treatise [2] for a brief introduction and main properties of the gamma function.

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Articles
Copyright
Copyright © The Mathematical Association 2013

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References

2. Artin, E., The gamma function, Holt, Rinehart and Winston, New York (1964).Google Scholar
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5. Borwein, P., Dykshoorn, W., An interesting infinite product, J. Math. Anal. Appl. 179 (1993) pp. 203207.Google Scholar
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7. Nanjundiah, T. S., Van der Pol's expressions for the gamma function, Proc. Amer. Math. Soc. 9 (1958) pp. 305307.Google Scholar
8. Weisstein, E., Euler-Mascheroni constant. From MathWorld, A Wolfram Web Resource. http://mathworld.wolfram.com/Euler-MascheroniConstant.html Google Scholar