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from common import sieve
primes = sieve(30000).primes()
prime_list = list(primes)
prime_list.sort()
def is_prime(n):
if n in primes:
return True
for p in prime_list:
if p*p > n:
return True
if n % p == 0:
return False
return True
def count_primes(numbers):
prime = 0
for n in numbers:
if is_prime(n):
prime += 1
return prime
#numbers = [1, 3, 5, 7, 9]
prime_count = 3
number_count = 5
level = 2
last = 9
while 10*prime_count >= number_count:
step = 2 * level
numbers = [last+step, last+2*step, last+3*step, last+4*step]
prime_count += count_primes(numbers)
number_count += 4
level += 1
last += 4*step
print 2*(level-1) + 1
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