Prototyping raw image sequence assignment (2013)

Assignment: In 50 lines or less of Python code, create a 1 second long animation by generating 25 frames of an image sequence.

See: Raw image, Raw image sequence

Results

To be posted / linked to here. Please post both your code (again, PURE python -- no libraries and less than 50 lines) + the resulting image (converted to GIF and uploaded to the wiki).