Tower of hanoi solver

Python, 76 chars

def S(n,a,b):
 if n:S(n-1,a,6-a-b);print n,a,b;S(n-1,6-a-b,b)
S(input(),1,3)

For instance, for N=3 it returns:

1 1 3  (move disk 1 from peg 1 to peg 3)
2 1 2  (move disk 2 from peg 1 to peg 2)
1 3 2  (move disk 1 from peg 3 to peg 2)
3 1 3  ...
1 2 1
2 2 3
1 1 3

Perl - 54 chars

for(2..1<<<>){$_--;$x=$_&-$_;say(($_-$x)%3,($_+$x)%3)}

Run with perl -M5.010 and enter the number of discs on stdin.

Output format:

One line per move, first digit is from peg, second digit is to peg (starting from 0)

Example:

02 -- move from peg 0 to peg 2
01
21
02
10
12
02

GolfScript (31 25 24 chars)

])~{{~3%}%.{)3%}%2,@++}*

With thanks to Ilmari Karonen for pointing out that my original trs/permutations could be shortened by 6 chars. By decomposing them as a product of two permutations I managed to save one more.

Note that factoring out the 3% increases length by one character:

])~{{~}%.{)}%2,@++}*{3%}%

---

Some people have really complicated output formats. This outputs the peg moved from (numbered 0, 1, 2) and the peg moved to. The spec doesn't say to which peg to move, so it moves to peg 1.

E.g.

$ golfscript hanoi.gs <<<"3"
01021201202101