def is_all_faster(min_t=0):
for n in itertools.count(1):
t = n * (2 * n - 1)
if is_pentagonal(t) and t > min_t:
yield t
def is_all(min_t=0):
for n in itertools.count(1):
t = n * (n + 1) / 2
if is_pentagonal(t) and is_hexagonal(t) and t > min_t:
yield t
