Grigory M
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 Apr10 comment A reference for a combinatorial identity The second form looks like just a Vandermonde's identity ($\binom{i+k-1}i=\pm\binom{-k}i$ etc). Apr8 comment Stiefel-Whitney classes with Z-coefficients (Re: The only problem I see is with the Steenrod square operation which may be undefined for integral coefficients) Well, yes there are no non-trivial stable operations from H(-;Q) to H(-;Q), after all... Apr7 reviewed Close Arrange white and colored balls in cells Apr7 reviewed Close Simplifying $\arctan\left(\frac{1}{\tan \alpha}\right)$ Apr6 reviewed Leave Open Every prime is maximal in a Jacobson ring? Apr6 reviewed Close Riemann integrable functions-True or False Apr6 reviewed Close $\frac{1}{2}!$ aka $\Gamma(\frac{3}{2})$ Apr5 reviewed Close Find $\lim_{x\to 0} \frac{\sin\left((2t+1)x\right)}{(t+1)x}$ Apr5 reviewed Close How can i integrate the equation below and simplify exp(e^t)? Apr5 reviewed Close finding all singularities of $f(z)= (z \sin z ) / (1-\cos z)$ Apr5 reviewed Close Can modulo(remainder) be distribute over division? Apr5 reviewed Leave Open Evaluating $\sum_{n=1}^\infty \frac{1}{n^2 2^n}$ Apr5 reviewed Close Algebra: Integral extension Apr5 reviewed Close Commutative algebra: Integral extension Apr5 reviewed Close Prove that $1+20^1+20^2+\cdots+20^{21}\equiv 0\pmod{23}$ Apr5 reviewed Close Floor and Ceiling Proofs Apr5 reviewed Leave Closed Projection of a Jinc is a Sinc Apr5 reviewed Close If 12 identical balls are to be placed in 3 identical boxes, then the prob that one of boxes contains exactly 3 balls is? Apr5 reviewed Leave Open Proving real polynomials of degree greater than or equal to 3 are reducible Apr5 reviewed Leave Open Examples of functors that preserves products but not equalizers, and vice versa.