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297
Answers
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142
Should the formula for the inverse of a 2x2 matrix be obvious?
Feb 21 '12 at 4:38
56
How good is Kamenetsky's formula for the number of digits in n-factorial?
Aug 26 '11 at 3:49
49
Parity of $\lfloor 1/(x y) \rfloor$ not equally distributed
Oct 19 '14 at 3:42
47
Absolute value inequality for complex numbers
May 21 '14 at 5:42
45
Is there a “classical” proof of this $j$-value congruence?
Jun 5 '11 at 0:23
44
There's something strange about $\sqrt{d\big(j(\tau)-1728\big)}$
Jan 16 '14 at 6:31
44
the following inequality is true，but I can't prove it
Jun 8 '13 at 3:50
41
Alternating sum of square roots of binomial coefficients
Jan 6 '12 at 6:53
41
Checkmate in $\omega$ moves?
May 1 '11 at 21:49
40
Heuristically false conjectures
Jul 30 '12 at 5:14
38
Are there infinitely many integer-valued polynomials dominated by $1.9^n$ on all of $\mathbb{N}$?
Aug 26 '13 at 1:54
38
A question on maps from $\mathbb{Z}/p\mathbb{Z}$ to itself
Jul 8 '13 at 5:02
38
Does $(x^2 - 1)(y^2 - 1) = c z^4$ have a rational point, with z non-zero, for any given rational c?
May 19 '12 at 21:51
36
On an example of an eventually oscillating function
Feb 28 at 3:09
35
How to decide this function takes integer values?
Jun 8 '11 at 3:20
33
cube + cube + cube = cube
May 5 '13 at 18:39
32
Minimum value of $|p(1)|^2+|p(2)|^2 +…+ |p(n+3)|^2$ over all monic polynomials $p$
Jul 6 at 2:29
32
A 14th and 26th-power Dedekind eta function identity?
Sep 17 '12 at 4:11
32
Is there any sequence $a_n$ of nonnegative numbers for which $\sum_{n \geq 1}a_n^2 <\infty$ and $\sum_{n \geq 1}\left(\sum_{k \geq 1}\frac{a_{kn}}{k}\right)^2=\infty$?
Jun 11 '11 at 4:41
31
Contest problems with connections to deeper mathematics
Jul 7 '11 at 19:56
30
Is there anything special about the Riemann surface $y^2 = x(x^{10}+11x^5-1)$?
Mar 1 '12 at 7:00
29
Groups in which all characters are rational.
Jun 24 '13 at 5:41
29
Matrix inequality $(A-B)^2 \leq c (A+B)^2$ ?
Jan 10 '12 at 6:08
27
Are nontrivial integer solutions known for $x^3+y^3+z^3=3$?
Jun 2 '11 at 14:31
27
Checkmate in $\omega$ moves?
May 3 '11 at 19:49
26
Is Weil's bound for Kloosterman sums ever attained?
May 16 '14 at 1:57
26
Jumping in the integers
Sep 4 '11 at 14:25
25
Which Diophantine equations can be solved using continued fractions?
Oct 13 '11 at 2:42
24
Szemeredi's theorem in the Gaussian integers
Aug 10 '14 at 5:51
24
Non-chaotic bouncing-ball curves
Aug 25 '13 at 2:14
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