def find_largest(up_to_number):
'''
Finds longest consecutive primes that add up to a prime.
'''
primes = erat(up_to_number)
max_length = len(primes)
current_sum = sum(primes)
def check_length(length, current_sum):
'''
Helper function.
'''
start = 0
end = length
working_val = current_sum
while end < up_to_number:
if working_val >= up_to_number:
break
elif isprime(working_val):
return working_val
working_val += primes[end] - primes[start]
start+=1
end+=1
return False
for length in range(max_length-1,0,-1):
current_sum -= primes[length]
result = check_length(length, current_sum)
if result:
return result
def test_erat(self):
for i in range(2, 544):
self.assertEqual(sieves.erat(i), self.primes_below(i))
def test_erat_empty(self):
# Check that erat() returns an empty list for values below 2.
for i in (1, 0, -1, -17):
self.assertEqual(sieves.erat(i), [])
def test_erat_returns_list(self):
self.assertTrue(isinstance(sieves.erat(10), list))
def test_erat_empty(self):
# Check that erat() returns an empty list for values below 2.
for i in (1, 0, -1, -17):
self.assertEqual(sieves.erat(i), [])
def test_erat(self):
for i in range(2, 544):
self.assertEqual(sieves.erat(i), self.primes_below(i))
def test_erat_returns_list(self):
self.assertTrue(isinstance(sieves.erat(10), list))
def find_ways(num): primes = erat(num) return primes
