Python

def triangles():
	L = [1]
	while True:
		yield L
		L = [sum(i) for i in zip([0] + L, L + [0])]

# Output of
#
# n = 0
# for t in triangles():
#	print(t)
#	n = n + 1
#	if n == 10:
#		break
#
# is:
#
# [1]
# [1, 1]
# [1, 2, 1]
# [1, 3, 3, 1]
# [1, 4, 6, 4, 1]
# [1, 5, 10, 10, 5, 1]
# [1, 6, 15, 20, 15, 6, 1]
# [1, 7, 21, 35, 35, 21, 7, 1]
# [1, 8, 28, 56, 70, 56, 28, 8, 1]
# [1, 9, 36, 84, 126, 126, 84, 36, 9, 1]