def Agx_gener():
"""
>>> list(islice(Agx_gener(), 20))[-1]
211345365
"""
for a, b in skip(g(), 1):
if b % 5 == 2:
yield (b - 7) / 5
def f(n):
"""
>>> f(12)
1118049290473932
"""
s, index = 0, 0
for a, b in skip(convergent_continued_fraction((2, [4])), 1):
if b * b * 5 - a * a == 1:
s += b
index += 1
if index >= n:
return s
def generator():
for b, a in skip(convergent_continued_fraction((1, [2])), 1):
if a * a * 2 - b * b == 1:
yield (b - 1)/ 2, (b + 1) / 2, a
