Talk:Pochhammer symbol

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There is an inconsistency in notation between this page and the `Hypergeometric Series' page. One uses the downstairs index for the falling factorial and one for the rising factorial. I don't know which is standard, so I'm not prepared to correct the appropriate page, but I thought they should be consistent, so I'm pointing it out here. —Preceding unsigned comment added by 152.2.6.241 (talk • contribs)

But this article explicitly says at the outset that there are TWO notational conventions: one that is standard in combinatorics and another that is standard in special functions.
You need to actually read it in order to understand what it says. Michael Hardy 23:16, 24 May 2007 (UTC)


It is, of course, obvious that (a)(n) = (a + n − 1)n. No, it is not obvious that this is the case. Instead of putting "it is obvious" or "it is trivial" could you please put how it is derived for people who do not understand like myself and many other students? —Preceding unsigned comment added by 129.81.123.46 (talk) 03:28, 13 December 2007 (UTC)

I tried to rephrase the sentence to make it clearer, but it is immediately obvious from the definitions. (a)(n) is defined as (a)(a+1)(...)(a+n-1). (a+n-1)n is defined as (a+n-1)(a+n-2)(...)(a). These are just the same product written in a different order. This is not obvious only to someone who doesn't know what the two symbols mean. 152.3.47.94 (talk) 05:45, 6 February 2008 (UTC)