Coprime : When two numbers have no common factors other than 1.
F.e. 21 and 22 are coprime, 21 and 24 are not.
#coprime generation
def farey(limit):
'''Fast computation of Farey sequence as a generator'''
# n, d is the start fraction n/d (0,1) initially
# N, D is the stop fraction N/D (1,1) initially
pend = []
n = 0
d = N = D = 1
while True:
mediant_d = d + D
if mediant_d <= limit:
mediant_n = n + N
pend.append((mediant_n, mediant_d, N, D))
N = mediant_n
D = mediant_d
else:
yield n, d
if pend: n, d, N, D = pend.pop()
else: break
