How to put a character above another in LaTeX?

Question

How to put a symbol above (on the head) of another? For example, I want to create something similar in one line.

a # 

ie, a above # .

The effect should be almost the same as $#^a$ , except that a is on top, not top right of # .

Answer 1

Use \overset{above}{main} in math mode. In your case, \overset{a}{\#} .

Answer 2

If you use # as the operator, consider defining a new operator for it:

 \newcommand{\pound}{\operatornamewithlimits{\#}} 

Then you can write things like \pound_{n = 1}^N and get:

alt text http://i46.tinypic.com/2889j41.png

Answer 3

 ${a \atop \#}$ 

or

 ${a \above 0pt \#}$