john mangual
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 2d reviewed Close A proposition in discrete math 2d awarded Custodian 2d reviewed Leave Open A question about $0/1$ matrices and a question about counting sums. 2d revised Where are the roots going? added 357 characters in body 2d answered Where are the roots going? Oct 6 answered Density of the image of the set $\lbrace (x,x), x\in \mathbb{Z} \rbrace$ in $\mathbb{Z_{p}} \times \mathbb{Z}_{q}$ Oct 6 answered Prove that for all $n\in\mathbb{N}$, $\sqrt{n(n+1)}$ is not an integer. Oct 1 answered Is entropy of prime numbers smaller? Sep 28 comment How many different values can $(x^2 + y^2, x^2 + 2y^2 )$ have mod 4? ...and surely $f$ is multiplicative so we are done! Sep 28 revised How many different values can $(x^2 + y^2, x^2 + 2y^2 )$ have mod 4? added some data points from my own computations to help with a possible guess for the formula Sep 28 revised How many different values can $(x^2 + y^2, x^2 + 2y^2 )$ have mod 4? added 70 characters in body Sep 28 comment How many different values can $(x^2 + y^2, x^2 + 2y^2 )$ have mod 4? @lulu Here's a nice general question: what fraction of the $m^2$ possible values can $(x^2 + y^2 , x^2 + 2y^2)$ take mod $m$ ? I can still change it... Sep 28 asked How many different values can $(x^2 + y^2, x^2 + 2y^2 )$ have mod 4? Sep 24 revised Are conjugacy classes in $SO(\mathbb{Z}[\frac{1}{2}])$ infinite? added 155 characters in body Sep 24 asked Are conjugacy classes in $SO(\mathbb{Z}[\frac{1}{2}])$ infinite? Sep 21 comment Is the term $E\left[Z^3E[Z\mid Y] \right]$ positive or negative? @Boby is this really for all random variables $Y$ ? Sep 18 revised Embedding of symmetric groups into orthogonal groups added 539 characters in body Sep 18 answered Embedding of symmetric groups into orthogonal groups Sep 17 revised Proof of $\sum_{d|n} {\tau}^3(d)=\left(\sum_{d|n}{\tau}(d)\right)^2$ (not standard proof) added 1269 characters in body Sep 17 asked Translation of a certain proof of $(\sum k)^2 = \sum k^3$