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abnry
  • Member for 11 years, 9 months
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26 votes
2 answers
3k views

Continuous generalization of $\sum_{k=0}^n {n \choose k} = 2^n$?

20 votes
1 answer
2k views

How many different shapes can I make with this toy?

17 votes
4 answers
4k views

Proving the irrationality of $e^n$

17 votes
1 answer
2k views

What finite groups always have a square root for each element?

15 votes
2 answers
626 views

What are all finite groups such that all isomorphic subgroups are identical?

14 votes
3 answers
7k views

What is Nassim Taleb's criticism of 538's election model?

13 votes
2 answers
534 views

Does there exist a finite group whose automorphism group is simple?

12 votes
2 answers
5k views

Quadratic ODE systems

11 votes
1 answer
659 views

Expected time to completely cover a square with randomly placed smaller squares

11 votes
1 answer
2k views

Feynman's Algorithm for computing a logarithm of a number in [1,2]

9 votes
3 answers
698 views

At least one prime between $\sqrt{n}$ and $n$?

9 votes
2 answers
1k views

Estimating rate of blow up of an ODE

8 votes
2 answers
499 views

Does there exist $\alpha \in \mathbb{R}$ and a field $F \subset \mathbb{R} $ such that $F(\alpha)=\mathbb{R}$?

7 votes
1 answer
4k views

What are the conditions for a compact, convex set to be homeomorphic to the closed unit ball in the plane?

7 votes
1 answer
213 views

Prove $18080108080 \sum_{k=0}^{1560-1} 10^{10k}+1$ is prime

7 votes
4 answers
231 views

Prove $(x+r_1) \cdots (x+r_n) \geq (x+(r_1 \cdots r_n)^{1/n})^{n}$.

7 votes
1 answer
349 views

What is an example of a power automorphism of a group that isn't a universal power automorphism?

6 votes
2 answers
95 views

Subgroup $H$ of $\mathrm{GL}_n(\mathbf{R})$ where elements are of $H$ are matrices with only positive entries

6 votes
1 answer
284 views

Are all power automorphisms of a finite abelian group of the form $f(x)=x^n$?

6 votes
1 answer
108 views

How does the size of the set $A(R) = \{(a,b) \; | \; a,b \in N \times N, \; \gcd(a,b) = 1, \; a^2 + b^2 \leq R^2\}$ grow?

6 votes
2 answers
2k views

Advection Diffusion Equation on Semi-Infinite Domain

6 votes
1 answer
203 views

Can you always combine the dual of an Archimedean Solid with itself like an icosidodecahedron?

5 votes
4 answers
156 views

How to compute $\lim_{t \to \infty} \int_0^1 \sqrt{1+t^2 x^{2t-2}} dx$ without using arclength?

5 votes
3 answers
231 views

Looking for more "exotic" classes of polyhedra

5 votes
1 answer
138 views

What groups have the property: All nontrivial isomorphic subgroups have a nontrivial intersection?

5 votes
2 answers
256 views

For any positive integer $k$, are there always primes $p$ and $q$ such that $q-p=2^k$?

4 votes
1 answer
171 views

Does a circle minimize mean squared curvature in the plane?

4 votes
1 answer
71 views

Does $f(g(s))=g(s)$ and $g(f(s))=f(s)$ imply $f(f(s))=f(s)$ and $g(g(s))=g(s)$?

4 votes
2 answers
127 views

Examples of a group $G$ with a non-trivial homomorphism $f:G \to Z(G)$

4 votes
1 answer
146 views

How does $\sum p(k)$ grow asymptotically where $p(k)$ is the smallest prime factor of $k$?