Is there a way? multiple images to looping video via ffmpeg?

Question

I want to use ffmpeg to create a 15 second looping video from images for posting to instagram.

For instance:

Camera takes 3 pictures

Each image plays for 2 frames (3 images = 6 frames)

After 6 frames, video should loop until desired video length has been achieved

Final output is 15 seconds long at 30fps

Is this possible??