Python address index +1 with list comprehension
EDIT: As pointed out by an anonymous user, my first version did not skip numbers that follow an even number of 13's.

Use an iterator. While you for loop over an iterator you can skip items with next.

def lucky_nums(nums):
    nums = iter(nums)
    for i in nums:
        if i == 13:
            while next(nums) == 13:
                pass
        else:
            yield i

print sum(lucky_nums([12,13,14,15]))