In this post OP was asked to derive the Catalan numbers. I am not sure how to react. As posted, there was no background. OP showed no effort. If I were asked the question and had no clue how to approach it, I would compute small values and ask OEIS, which would be a success. Once you find the term Catalan numbers you should be all set. if you haven't heard of the Catalan numbers it seems it would be very hard to find them. As OP has the formula, computing small values and doing a web search should get there as well. Should we close as homework showing no effort? My hesitation comes from feeling that this is a reasonable problem to have no clue how to attack.
It is reasonable for a student to have "no clue", but a question should not simply consist of
[copy-paste of problem statement]
I have no idea. kthxbai.
I would like to remind everyone that there is no option to close a question as "homework showing no effort". The closest official close reason we have is "missing context or other details," and to repeat once again: context ≠ effort. As per our "asking good questions" page, context can come in many forms, including
- providing some motivation;
- indicating where the question comes from;
- indicating background;
- giving full references;
- giving definitions.
I note that the linked question includes this phrase
The answer given in my textbook is...
Wouldn't it be grand if we were told what textbook that was? (And also where in it the question was located.) In my opinion that one small piece of information would go a long way to providing context (not effort) to the question. At the very least it would give some clue about the mathematical background of the asker. It would also allow others with the same question from the same unnamed textbook to find it in the future (which is important since Stack Exchange sites are supposed to serve as repositories of questions and answers).