Math Symbols

$$ a_n\frac {x^n} {|G|}$$

Wikipedia Latex
https://en.wikipedia.org/wiki/Help:Displaying_a_formula

$${n \choose k} = \frac{n!}{k! (n-k)!}$$

$$\sum_{i=0}^{n-1} i$$

Sets
http://math.wikia.com/wiki/Set

symbols
http://typefacts.com/keyboard-shortcuts http://math.wikia.com/wiki/Greek_alphabet

– em dash, long dash

$$\mathcal{B}^k \rightarrow \mathcal{B}$$.

$$f|_{X}=f$$

\mathbf {S}

tables in Wikia
http://community.wikia.com/wiki/Help:Wikitext/table_examples

Wiki Markup
https://en.wikipedia.org/wiki/Help:Wiki_markup

https://en.wikipedia.org/wiki/Help:Displaying_a_formula