New answers tagged re-open
-1
Undeleted, reopened, reclosed (as duplicate)
Yesterday I posted this this question. When I checked it last night, it had the two sound-looking answers you see. I woke up today to find it had been not just closed but completely deleted. This seems to me completely preposterous. It's pretty clearly not a homework question, but a reasonably deep integral ...
-1
Deleted, Undeleted
Proving $\sum_{k = 1}^{n} (-1)^{k}{n \choose k} {nk \choose m} = 0$.
Question: Show that $\sum_{k = 1}^{n} (-1)^{k}{n \choose k} {nk \choose m} = 0$ for $1\le m\le n-1$.
I think this was a nice combinatorics question, with two well-written answers that offer interesting perspectives, in addition to an answer of my own. I see why it was ...
0
Reopened
Please reopen https://math.stackexchange.com/q/4074358.
I have also voted for closing the question as a duplicate but retracted the vote after the question was edited.
It is clear from the content of the edited question that its issue was a search for an error in the OP solution (and not for a correct way of solving the problem). In this sense it ...
Top 50 recent answers are included
