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17 votes
1 answer
1k views

What is $\mathcal{R}$?

First of all, I am asking this question entirely out of curiosity. It basically randomly popped out of my mind. So I am asking for the value of an infinite series. Let's call it, $\mathcal{R}=\sum_{n=...
Rounak Sarkar's user avatar
2 votes
1 answer
152 views

Closed form of $\prod_{i=0}^{N}\big(i!\big)^{{N}\choose{i}}$

I was wondering if there is a closed form for $$\prod_{i=0}^{N}\big(i!\big)^{{N}\choose{i}}$$ I know that for $$\prod_{i=0}^{N}\big(i!\big)=G(N+2)$$ where we have expressed it as Barnes G-function. ...
Wiliam's user avatar
  • 493
1 vote
0 answers
68 views

Closed form for product over Gamma function

Is there a "closed form" (with which I mean an expression not involving an indexed sum or product) for any of these four products? $$\prod_{k=1}^{n} \Gamma(\frac{x}{k*2+1})$$ $$\prod_{k=1}^{n} \Gamma(...
SmallestUncomputableNumber's user avatar
4 votes
1 answer
182 views

Product identity for $n^n$

I came across the rather nice identity \begin{align} &&\frac{(-n)^{n-1} \Gamma (n+1)}{(1-n)_{n-1}}&&\tag{1}&\\ \\ &=&\prod _{k=1}^{n-1} \frac{(k+1) n^2}{n^2-k n}&&\...
martin's user avatar
  • 9,018