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Jul 2, 2018 at 10:15 answer added Gro-Tsen timeline score: 9
Jul 2, 2018 at 4:36 history edited Alexey Ustinov CC BY-SA 4.0
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Jul 2, 2018 at 4:35 answer added Alexey Ustinov timeline score: 1
Feb 26, 2018 at 16:30 history edited Adam P. Goucher CC BY-SA 3.0
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Jul 16, 2013 at 11:40 history edited john mangual CC BY-SA 3.0
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Jul 10, 2013 at 23:31 comment added john mangual The distribution of quadratic forms $\mod p$ seems intimately tied with quadratic reciprocity math.ucsd.edu/~kedlaya/2012s.pdf
Jul 10, 2013 at 14:57 comment added john mangual These solutions are quite varied, using Fourier analysis, Probability and trees and quadratic reciprocity. Doesn't Hensel's lemma get you integer solutions to quadratic forms as well?
Jul 10, 2013 at 14:24 comment added Noam D. Elkies Yet another MO source for counting solutions of $\sum_{i=1}^n x_i^2 \equiv 1 \bmod p$: mathoverflow.net/questions/1420/…
Jul 10, 2013 at 14:00 comment added john mangual @AbhinavKumar I take it with Chinese Remainder and Hensel's lemma, formulas like these should exist for any quadratic form. It also means the solution sets are quite regular. Thank you.
Jul 10, 2013 at 13:47 history edited john mangual CC BY-SA 3.0
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Jul 10, 2013 at 13:41 comment added Noam D. Elkies Typo: the formula for a circle should be $x^2+y^2=1$ (or $\equiv 1$), not $x^2+y^2+z^2=1$.
Jul 10, 2013 at 13:40 comment added Noam D. Elkies For the number of solutions mod $p$ to $\sum_{i=1}^n x_i^2 = 1$, see mathoverflow.net/questions/69576/sum-of-squares-modulo-a-prime
Jul 10, 2013 at 13:28 comment added Abhinav Kumar The formula must be a multiplicative function, by CRT (since you're counting number of solutions to some congruence). So you need to compute the number of solutions mod prime powers $p^k$. Do this for $k = 1$ and then use Hensel (if $p = 2$, you might have to start with $k = 3$). This sort of "mass" formula is common when you consider representation numbers of quadratic forms. For instance, see the book "Rational quadratic forms" by Cassels.
Jul 10, 2013 at 13:06 comment added john mangual I wonder if these functions have appeared in the "serious" number theory literature and why. I had thought of this while trying to answer mathoverflow.net/questions/136131/calculus-over-finite-fields on this site.
Jul 10, 2013 at 13:05 history edited john mangual CC BY-SA 3.0
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Jul 10, 2013 at 12:45 history asked john mangual CC BY-SA 3.0