4:50 AM
A new tag . But there already is a tag called .
0

Consider the following lacunary sum with parameter $x$: $$S(x)=\sum_{n=5}^{\infty}\sin^2\left(\frac{x\Gamma(n)}{n}\right).$$ As we can see for $x=\frac{\pi}{2}$ the sum becomes$$\sum_p\cos^2\left(\frac{π}{2p}\right)$$ where $p$ runs through all primes. What are some non trivial properties of $S... I have edited the tags on that question. 0 Consider the following lacunary sum with parameter$x$: $$S(x)=\sum_{n=5}^{\infty}\sin^2\left(\frac{x\Gamma(n)}{n}\right).$$ As we can see for$x=\frac{\pi}{2}$the sum becomes$$\sum_p\cos^2\left(\frac{π}{2p}\right)$$ where$p$runs through all primes. What are some non trivial properties of$S...

2 hours later…
6:42 AM
Classification of Platonic solids - recently bumped by this edit. Should the tag or some similar tag be added? What is the tag closest to the topic of Platonic solids?
9

My question is very basic: where can I find a complete (and hopefully self-contained) proof of the classification of Platonic solids? In all the references that I found, they use Euler's formula $v-e+f=2$ to show that there are exactly five possible triples $(v,e,f)$. But of course this is not a ...

8 hours later…
2:30 PM
@MartinSleziak Perhaps ? It seems to be a larger tag than .

3 hours later…
5:54 PM
Thanks for the response! I have added that tag.
12

My question is very basic: where can I find a complete (and hopefully self-contained) proof of the classification of Platonic solids? In all the references that I found, they use Euler's formula $v-e+f=2$ to show that there are exactly five possible triples $(v,e,f)$. But of course this is not a ...