Create 147-Easy.py

You must write code that verifies the awarded points for a fictional sport are valid. This sport is a simplification of American Football[2] scoring rules. This means that the score values must be any logical combination of the following four rewards:
6 points for a "touch-down"
3 points for a "field-goal"
1 point for an "extra-point"; can only be rewarded after a touch-down. Mutually-exclusive with "two-point conversion"
2 points for a "two-point conversion"; can only be rewarded after a touch-down. Mutually-exclusive with "extra-point"
A valid score could be 7, which can come from a single "touch-down" and then an "extra-point". Another example could be 6, from either a single "touch-down" or two "field-goals". 4 is not a valid score, since it cannot be formed by any well-combined rewards.

Challenge Taken From:
http://www.reddit.com/r/dailyprogrammer/comments/1undyd/010714_challenge_147_easy_sport_points/