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1d
revised How to calculate $ \sum_{n=1}^{15}n(n!) = ? $
edited body
2d
revised Finding closed form expression for a multiple sum.
deleted 2 characters in body
Feb
4
revised Combinatorial argument for $\sum\limits_{k=i}^{n}\binom{n}{k}\binom{k}{i} = \binom{n}{i}2^{n-i}$
edited tags; edited title
Feb
4
revised Possible closed form or approximation?
deleted 3 characters in body; edited tags
Feb
1
revised why is the limit as n goes to infinity of $(1+\frac{1}{n}+\frac{200}{n^2})^n = e$?
added 14 characters in body
Feb
1
revised What is sample variance of sample variance, and what is theoretical sampling distribution?
added 1 character in body; deleted 1 character in body; edited body; added 1 character in body
Jan
25
revised Prove $\sum\limits_{i=1}^{n-k} (-1)^{i+1} \cdot \tfrac{(k-1+i)!}{k! \cdot(i-1)!} \cdot \tfrac{n!}{(k+i)! \cdot (n-k-i)!}=1$
edited body
Jan
24
revised Show that $\lim_{n\to\infty}n+n^2 \log\left(\frac{n}{n+1}\right)= 1/2$
edited body
Jan
20
revised Why do I get one extra wrong solution?
edited tags
Jan
18
revised Round table seating probability question
edited tags
Jan
13
revised finding the probability of not being answered more than two calls!
added 9 characters in body
Jan
11
revised How to prove $\sum_{i=1}^ki^k(-1)^{k-i}\binom {k+1}{i} =(k+1)^k$
edited tags
Jan
10
revised How far can you go with the fact that “powers beat logs”?
deleted 3 characters in body
Jan
8
revised $\lim_{x \to 1} \frac{\ln(x^3)}{x^2-1}$
added 3 characters in body
Jan
6
revised Conditional Probability about balls in a bag
added 117 characters in body
Dec
27
revised Find the recurrence formula for $\int \frac{dx} {(1+\sin x)^n}$
added 6 characters in body
Dec
25
revised Calculate $\lim_{n \to \infty}\binom{2n}{n}$ without using L'Hôpital's rule.
added 54 characters in body; added 1 character in body
Dec
23
revised In how many ways can 5 identical rings be worn in 4 fingers of a hand.
edited tags
Dec
16
revised Prove $\frac{x}{\sqrt{1+x^2}} \lt \arctan x$ for every $x \gt 0$
added 2 characters in body
Dec
9
revised How many arrangements of GRACEFUL…
added 18 characters in body