Grigory M
Reputation
11,615
365/400 score
 Oct 3 answered Area of hyperbolic triangle definition Jun 20 answered Combinatorial interpretation of identity: $\sum_{j=0}^b\binom{b}{j}^2\binom{n+j}{2b}=\binom{n}{b}^2$ Jun 20 answered Alternative way to count the number of solutions to the equation $x^2 + y^2 = -1$ over $\Bbb Z /p$ Jun 17 answered Counting the number of solutions of equation $x^2 + y^2 = 1$ over $\Bbb Z/p$ Mar 30 asked Counter-example to exponential law for locally compact [non-Hausdorff] spaces Jan 11 answered A three variable binomial coefficient identity Jan 10 answered Combinatorial Identity $\sum_{k=1}^n (-1)^{k-1} \cdot q^{\frac{k(k-1)}{2}} \cdot \frac{\prod_{i=n-k+1}^n(1-q^i)}{\prod_{i=1}^k(1-q^i)} = 1$ Jan 10 answered Finite summation with binomial coefficients, $\sum (-1)^k\binom{r}{k} \binom{k/2}{q}$ Jan 8 answered Is this morphism of spectra zero in the stable homotopy category? Jan 3 answered Ramanujan-type trigonometric identities with cube roots, generalizing $\sqrt[3]{\cos(2\pi/7)}+\sqrt[3]{\cos(4\pi/7)}+\sqrt[3]{\cos(8\pi/7)}$ Dec 31 answered Proving $\sum_{k=0}^{2m}(-1)^k{\binom{2m}{k}}^3=(-1)^m\binom{2m}{m}\binom{3m}{m}$ (Dixon's identity) Dec 31 answered Binomial Sum Related to Fibonacci: $\sum\binom{n-i}j\binom{n-j}i=F_{2n+1}$ Dec 30 answered Polynomial with a root modulo every prime but not in $\mathbb{Q}$. Dec 30 answered How prove this \$\prod_{1\le i