Ehh... this is hard. Can't be done with ANSI C. The symbol for a superscript 2 is a special case however, there is an ASCII character for that, so you could do x^2, but nothing else. At least, not using printf. Here is the code for a program that displays a table of the ASCII characters and their corresponding values...
If you really need to do this, you're gonna need some graphics routines, which would mean allegro. I reccomend just using the ^ symbol to represent powers.
int main ()
int c, i;
// There are 256 ascii characters, from 0 to 255.
// A lot of the values just can't be displayed. For example, there is
// the newline character, a backspace character, a tab character, and
// probably the most entertaining one, the beep character.
for (c = 0; c < 256; )
// Adjust the stopping value for i accordingly.
for (i = 0; i < (80) / 7 && c < 256; i++, c++)
printf ("%3d %c ", c, c);
// Depending on stopping value, this may or may not be commented out.