Derek Jennings

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9,250 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	2,776

Mathematician, linguist and, unfortunately, ex-athlete.

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159 Answers

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39	Ways to evaluate $\int \sec \theta \, d \theta$
29	Proving $\prod_{j=1}^n \left(4-\frac2{j}\right)$ is an integer
24	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?

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9,250 Reputation

+10	Why is Pi equal to 3.14159…?
+10	Ways to evaluate $\int \sec \theta \, d \theta$
+10	Proving $\prod_{j=1}^n \left(4-\frac2{j}\right)$ is an integer
+10	Proof for an integral involving sinc function

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4 Questions

votes activity newest

24	The order of the number of integer pairs satisfying certain arithmetical function relationships
18	What is the smallest value of $n$ for which $\phi(n) \ne \phi(k)$ for any $k<n,$ where $n=4m$?
16	Formula for the harmonic series $H_n = \sum_{k=1}^n 1/k$ due to Gregorio Fontana
3	Is this analysis problem involving induction flawed?

86 Tags

174 sequences-and-series × 32	74 analysis × 11
161 calculus × 27	71 algebra-precalculus × 13
140 number-theory × 27	53 trigonometry × 6
111 combinatorics × 19	43 pi × 5
91 integral × 12	39 indefinite-integral

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6 Accounts

$Mathematics Stack Exchange$	Mathematics	9,250 rep	1640
	Personal Finance & Money	470 rep	28
	English Language & Usage	264 rep	25
	Area 51	221 rep	4
	French Language & Usage	177 rep	4

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Nice Answer × 23	Constituent
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Enlightened × 9	calculus
Taxonomist	sequences-and-series
Yearling × 2	Organizer

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