Fun programming puzzler

Problem:
Code a Morris Sequence.

Requirements:
- Use as few characters as possible. A character is defined by anything that is not a newline, tab, or space.
- Any programming language, esoteric or traditional, may be used.
- The program should be free of buffer overflows and an exception may never be thrown.
- Your program must be able to print out an infinite number of iterations.
- Each iteration must be printed and be on its own line.
- Any and all compilation arguments may be used.
- If the Extra Credit below is not used, the sequence must begin with "1" as the starting number.
- Assume the input is always valid.

Extra Credit:
Allow the user to input his own number to start the sequence.

Examples:

Input:

Code:

>>> morris

Output:

Code:

1
11
21
1211
111221
{And so on}

Input:

Code:

>>> morris 3

Output:

Code:

3
13
1113
3113
132113
{And so on}

Input:

Code:

>>> morris 131313

Output:

Code:

131313
111311131113
311331133113
13212321232113
{And so on}

Reference:
Stack Overflow