Extra primes: Difference between revisions
Add Python
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=={{header|Python}}==
<lang python>from itertools import *
from functools import reduce
class Sieve(object):
"""Sieve of Eratosthenes"""
def __init__(self):
self._primes = []
self._comps = {}
self._max = 2;
def isprime(self, n):
"""check if number is prime"""
if n >= self._max: self._genprimes(n)
return n >= 2 and n in self._primes
def _genprimes(self, max):
while self._max <= max:
if self._max not in self._comps:
self._primes.append(self._max)
self._comps[self._max*self._max] = [self._max]
else:
for p in self._comps[self._max]:
ps = self._comps.setdefault(self._max+p, [])
ps.append(p)
del self._comps[self._max]
self._max += 1
def extra_primes():
"""Successively generate all extra primes."""
d = [2,3,5,7]
s = Sieve()
for cand in chain.from_iterable(product(d, repeat=r) for r in count(1)):
num = reduce(lambda x, y: x*10+y, cand)
if s.isprime(num) and s.isprime(sum(cand)): yield num
for n in takewhile(lambda n: n < 10000, extra_primes()):
print(n)
</lang>
{{out}}
<pre>2
3
5
7
23
223
227
337
353
373
557
577
733
757
773
2333
2357
2377
2557
2753
2777
3253
3257
3323
3527
3727
5233
5237
5273
5323
5527
7237
7253
7523
7723
7727</pre>
=={{header|Raku}}==
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