User Robert D-B

17 votes

3 answers

991 views

Are there primes arbitrarily close to powers?

asked Nov 22, 2019 at 21:46

7 votes

1 answer

293 views

Is $f(\sqrt{x}) + f(-\sqrt{x})$ always rational?

asked Jan 14, 2020 at 20:29

6 votes

1 answer

330 views

How many triangular numbers have exactly $d$ divisors?

asked Feb 7, 2019 at 15:31

5 votes

1 answer

149 views

Why does Herstein add all these extra hypotheses for a "simple" modules proof?

asked Aug 7, 2018 at 17:23

5 votes

1 answer

116 views

A game that costs the square root of your winnings

asked Jan 31 at 22:01

4 votes

2 answers

151 views

How many graphs are "obviously" nonplanar?

asked Jan 8, 2019 at 22:50

4 votes

1 answer

181 views

Estimating $\sum_1^\infty e^{-k^2}$

asked Sep 8, 2015 at 1:55

4 votes

1 answer

59 views

Rings in which the "mistake" $(x + y) / d = x / d + y$ is justified

asked May 3, 2018 at 4:25

3 votes

2 answers

347 views

Contour integration and the central binomial coefficients

asked Oct 19, 2018 at 16:41

3 votes

1 answer

185 views

What "are" iterated Hom-spaces?

asked Jul 21, 2018 at 22:39

3 votes

1 answer

121 views

Does $e^x e^x$ really equal $e^{2x}$?

asked Apr 27, 2019 at 15:34

2 votes

0 answers

69 views

Are the reversed digits of $\pi$ equidistributed modulo 1?

asked Jul 17, 2019 at 13:59

2 votes

1 answer

69 views

Qual problem on the intersection of two surfaces

asked Aug 25, 2019 at 22:39

2 votes

1 answer

69 views

Does this equivalence relation characterize continued fractions?

asked Apr 16, 2020 at 22:36

2 votes

1 answer

572 views

If a finite group $G$ acts transitively on a set of order $p^m$, then so does any $p$-Sylow subgroup

asked Jun 23, 2020 at 21:32

2 votes

1 answer

429 views

Convergence in $L^1$ and uniformly bounded $L^4$ norm implies $L^2$ convergence

asked Dec 27, 2019 at 1:34

2 votes

2 answers

199 views

Maximizing $f(x, y, z) = xyz$ on the intersection of a cylinder and a plane

asked Apr 15, 2018 at 19:32

1 vote

0 answers

75 views

Reciprocal sum of sequences with Sylvester-like quadratic recurrence

asked Dec 26, 2018 at 23:00

1 vote

1 answer

26 views

Large graph connectivity implies both many and few edges?

asked Jan 6, 2019 at 19:21

1 vote

1 answer

49 views

Is the "term-matrix" of a $C$-finite sequence full rank?

asked Aug 27, 2018 at 18:41

1 vote

2 answers

247 views

Show that $\frac{d^2y}{dx^2}=-\frac{d^2x}{dy^2} / \left(\frac{dx}{dy}\right)^3$ is an identity

asked Jan 1, 2016 at 20:59

1 vote

3 answers

325 views

Prove that $2 \leq (1 + 1/n)^n$ without induction or binomial theorem

asked Feb 28, 2016 at 2:28

1 vote

0 answers

53 views

Proving alternate definitions of homogeneous functions are equivalent

asked May 15, 2016 at 21:18

1 vote

1 answer

110 views

Can you tile a heart with dominoes?

asked Mar 6, 2021 at 17:05

1 vote

0 answers

43 views

Exponential family hypercube summation identity

asked Jan 18, 2020 at 21:35

1 vote

2 answers

111 views

Second order recurrence with linear polynomial coefficients

asked Mar 10, 2020 at 3:40

1 vote

1 answer

96 views

Is the reverse of a previous prime always smaller?

asked Nov 23, 2019 at 22:22

1 vote

1 answer

624 views

Proving Fatou's lemma from the DCT

asked Feb 15, 2019 at 22:12

1 vote

1 answer

638 views

Generating function of even Fibonacci numbers

asked Apr 4, 2019 at 0:07

1 vote

1 answer

107 views

Creating a generating function for the Stirling transform

asked Jun 8, 2019 at 0:59

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39 Questions

Are there primes arbitrarily close to powers?

Is $f(\sqrt{x}) + f(-\sqrt{x})$ always rational?

How many triangular numbers have exactly $d$ divisors?

Why does Herstein add all these extra hypotheses for a "simple" modules proof?

A game that costs the square root of your winnings

How many graphs are "obviously" nonplanar?

Estimating $\sum_1^\infty e^{-k^2}$

Rings in which the "mistake" $(x + y) / d = x / d + y$ is justified

Contour integration and the central binomial coefficients

What "are" iterated Hom-spaces?

Does $e^x e^x$ really equal $e^{2x}$?

Are the reversed digits of $\pi$ equidistributed modulo 1?

Qual problem on the intersection of two surfaces

Does this equivalence relation characterize continued fractions?

If a finite group $G$ acts transitively on a set of order $p^m$, then so does any $p$-Sylow subgroup

Convergence in $L^1$ and uniformly bounded $L^4$ norm implies $L^2$ convergence

Maximizing $f(x, y, z) = xyz$ on the intersection of a cylinder and a plane

Reciprocal sum of sequences with Sylvester-like quadratic recurrence

Large graph connectivity implies both many and few edges?

Is the "term-matrix" of a $C$-finite sequence full rank?

Show that $\frac{d^2y}{dx^2}=-\frac{d^2x}{dy^2} / \left(\frac{dx}{dy}\right)^3$ is an identity

Prove that $2 \leq (1 + 1/n)^n$ without induction or binomial theorem

Proving alternate definitions of homogeneous functions are equivalent

Can you tile a heart with dominoes?

Exponential family hypercube summation identity

Second order recurrence with linear polynomial coefficients

Is the reverse of a previous prime always smaller?

Proving Fatou's lemma from the DCT

Generating function of even Fibonacci numbers

Creating a generating function for the Stirling transform