Stack Exchange

Derek Jennings

England, United Kingdom

top accounts reputation activity bookmarks subscriptions
Top Questions
Top Answers
93
Ways to evaluate $\int \sec \theta \, \mathrm d \theta$
math.stackexchange.com

65
Prove $0! = 1$ from first principles
math.stackexchange.com

38
Which is correct: “one or more is” or “one or more are”?
english.stackexchange.com

36
Different methods to compute $\sum\limits_{k=1}^\infty \frac{1}{k^2}$ (Basel problem)
math.stackexchange.com

32
Proving $\prod_{j=1}^n \left(4-\frac2{j}\right)$ is an integer
math.stackexchange.com

31
Evaluating the integral $\int_0^\infty \frac{\sin x} x \,\mathrm dx = \frac \pi 2$?
math.stackexchange.com

26
Why is $\pi $ equal to $3.14159…$?
math.stackexchange.com

25
Proof of $\int_0^\infty \left(\frac{\sin x}{x}\right)^2 \mathrm dx=\frac{\pi}{2}.$
math.stackexchange.com

25
Summing $\frac{1}{e^{2\pi}-1} + \frac{2}{e^{4\pi}-1} + \frac{3}{e^{6\pi}-1} + \cdots \text{ad inf}$
math.stackexchange.com

24
Common misconceptions about math
math.stackexchange.com

24
Formerly good at math, but after 12 years I've lost most of my skills. Now I need them once again. Any advice to grow them back?
math.stackexchange.com

20
Erroneous numerical approximations of $\zeta\left(\frac{1}{2}\right)$?
math.stackexchange.com

20
why is $\sum\limits_{k=1}^{n} k^m$ a polynomial with degree $m+1$ in $n$
math.stackexchange.com

19
Calculate $\pi$ precisely using integrals?
math.stackexchange.com

18
How to compute the series $\sum_{n=0}^\infty q^{n^2}$?
math.stackexchange.com

18
Which one result in mathematics has surprised you the most?
math.stackexchange.com

17
Are there any differences between “update” and “upgrade”?
english.stackexchange.com

16
List of interesting math videos / documentaries
math.stackexchange.com

16
Puzzle: digit $x$ appears $y$ times on this piece of paper…
math.stackexchange.com

16
Is there a proof that $\pi$ is an irrational number?
math.stackexchange.com

15
What is the importance of the Collatz conjecture?
math.stackexchange.com

15
Proving a binomial sum identity $\sum _{k=0}^n \binom nk \frac{(-1)^k}{2k+1} = \frac{(2n)!!}{(2n+1)!!}$
math.stackexchange.com

15
Proving $ \frac{\sigma(n)}{n} < \frac{n}{\varphi(n)} < \frac{\pi^{2}}{6} \frac{\sigma(n)}{n}$
math.stackexchange.com

14
If p is an odd prime, prove that $1^2 \times 3^2 \times 5^2 \cdots \times (p-2)^2 \equiv (-1)^{(p+1)/2}\pmod{p}$
math.stackexchange.com

13
$k^{2}+(k+1)^{2}$ being a perfect square for infinitely many $k$
math.stackexchange.com

13
Computing $\sum_{m \neq n} \frac{1}{n^2-m^2}$
math.stackexchange.com

12
Nth derivative of a function: I don't know where to start
math.stackexchange.com

12
How to prove the equality $\sum_{j=0}^n (x)^j (-1)^{n-j} \left\{{n \atop j}\right\} = x^n$?
math.stackexchange.com

12
Why is $\tau(n) \equiv \sigma_{11}(n) \pmod{691}$?
math.stackexchange.com

12
Identity involving Euler's totient function: $\sum \limits_{k=1}^n \left\lfloor \frac{n}{k} \right\rfloor \varphi(k) = \frac{n(n+1)}{2}$
math.stackexchange.com

1 2 3 4