Does there exists a finitely generated group which contains torsion elements of order p for all prime numbers p?

Solutions for POW 2022-11 are due July 4th (Saturday), 12PM, and it will remain open if nobody solved it.

For positive integers \(n \geq 2\), let \(a_n = \lceil n/\pi \rceil \) and let \(b_n = \lceil \csc (\pi/n) \rceil \). Is \(a_n = b_n\) for all \(n \neq 3\)?

Solutions are due May 13th (Friday), 6PM, and it will remain open if nobody solved it.

Show that there exist perfect squares a, b, c such that \(a^2 + b^2 = c^2\).

====== REVISED (2022-04-04) ======

I hope you noticed the day this problem appeared was April fool’s day. Show instead that there do not exist perfect squares a, b, c such that \(a^2 + b^2 = c^2\), provided that a, b, c are nonzero integers.

For any positive integer \(n \geq 2\), let \(B_n\) be the group given by the following presentation\[ B_n = < \sigma_1, \ldots, \sigma_{n-1} | \sigma_i \sigma_{i+1} \sigma_i = \sigma_{i+1} \sigma_i \sigma_{i+1}, \sigma_i \sigma_j = \sigma_j \sigma_i > \]where the first relation is for \( 1 \leq i \leq n-2 \) and the second relation is for \(|i-j| \geq 2\). Show that there exists a total order < on \(B_n\) such that for any three elements \(a, b, c\in B_n\), if \(a < b\) then \(ca < cb\). 

Let \(n, m\) be positive integers where \(m\) divides \(n\). When there exists a regular \(n\)-gon with area 1, what is the area of the largest regular \(m\)-gon inscribed in the \(n\)-gon in terms of \(n\) and \(m\)?

Say a natural number \(n\) is a cyclically perfect if one can arrange the numbers from 1 to \(n\) on the circle without a repeat so that the sum of any two consecutive numbers is a perfect square. Show that 32 is the smallest cyclically perfect number. Find the second smallest cyclically perfect number.

On the sphere of radius r, how many points one can put if any two points must be distance at least 1 apart? How fast does this number grow as a function in r?

Let X, Y be compact spaces. Suppose \(X \times Y\) is perfectly normal, i.e, for every disjoint closed subsets E, F in \(X \times Y\), there exists a continuous function \( f: X \times Y \to [0, 1] \subset \mathbb{R} \) such that \( f^{-1}(0) = E, f^{-1}(1) = F \). Is it true that at least one of X and Y is metrizable?

(added Sep. 11, 8AM: Assume further that \( X \times Y\) is Hausdorff.)

Determine if there exist infinitely many perfect cubes such that the sum of the decimal digits coincides with the cube root. If there are only finitely many, how many are there? 

Prove or disprove that if C is any nonempty connected, closed, self-antipodal (ie., invariant under the antipodal map) set on \(S^2\), then it equals the zero locus of an odd, smooth function \(f:S^2 -> \mathbb{R}\).