Derek Jennings

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9,260 reputation
1640
bio website homepage.ntlworld.com/…
location England, United Kingdom
age 52
visits member for 2 years, 9 months
seen Apr 30 '11 at 7:24
stats profile views 2,778

Mathematician, linguist and, unfortunately, ex-athlete.


159 Answers

newest activity votes
39
Ways to evaluate $\int \sec \theta \, d \theta$
29
Proving $\prod_{j=1}^n \left(4-\frac2{j}\right)$ is an integer
25
Summing $\frac{1}{e^{2\pi}-1} + \frac{2}{e^{4\pi}-1} + \frac{3}{e^{6\pi}-1} + \cdots \text{ad inf}$
21
Prove $0! = 1$ from first principles
21
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?
18
Why is Pi equal to 3.14159…?
18
Common misconceptions about math
17
Erroneous numerical approximations of $\zeta\left(\frac{1}{2}\right)$?
17
How to compute the series $\sum_{n=0}^\infty q^{n^2}$?
14
Is there a proof that $\pi$ is an irrational number?
14
why is $\sum\limits_{k=1}^{n} k^m$ a polynomial with degree $m+1$ in $n$
13
Computing $\sum_{m \neq n} \frac{1}{n^2-m^2}$
13
Puzzle: digit $x$ appears $y$ times on this piece of paper…
12
Solving the integral $\int_{0}^{\infty} \frac{\sin{x}}{x} \ dx = \frac{\pi}{2}$?
12
Proving a binomial sum identity
11
How to prove the equality $\sum_{j=0}^n (x)^j (-1)^{n-j} \left\{{n \atop j}\right\} = x^n$?
11
Nth derivative of a function: I don't know where to start
10
Show that $\displaystyle \sum_{k \ge 0}\frac{1}{k^2+k-\alpha} = \frac{\pi}{\sqrt{4\alpha+1}}\tan\left(\frac{1}{2}\pi\sqrt{4\alpha+1}\right)$
10
Fermat's Last Theorem - Special Case of Sophie Germain Primes
10
Why is $\tau(n) \equiv \sigma_{11}(n) \pmod{691}$?
10
Proving $ \frac{\sigma(n)}{n} < \frac{n}{\varphi(n)} < \frac{\pi^{2}}{6} \frac{\sigma(n)}{n}$
10
Different methods to compute $\sum\limits_{n=1}^\infty \frac{1}{n^2}$
9
Calculate $\pi$ precisely using integrals?
9
If p is an odd prime, prove that $1^2 \times 3^2 \times 5^2 \cdots \times (p-2)^2 \equiv (-1)^{(p+1)/2}\pmod{p}$
9
List of Interesting Math Videos/ Documentaries
9
How to derive the following identity?
9
Proof for an integral involving sinc function
9
Identity involving Euler's totient function: $\sum \limits_{k=1}^n \left\lfloor \frac{n}{k} \right\rfloor \varphi(k) = \frac{n(n+1)}{2}$
9
Evaluating the improper integral $\int\limits_{0}^{\infty} \frac{x^{a-1} - x^{b-1}}{1-x} \ dx $
8
Show that product of primes, $\prod_{k=1}^{\pi(n)} p_k < 4^n$
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