Project Euler

The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.

Find the sum of all the primes below two million.

A little sieve of Eratosthenes…

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# sieve of Eratosthenes
def sieve(n):
  primes = range(2,n)
  x = 0
  while primes[x] < n**0.5:
    primes = [y for y in primes if y==primes[x] or y%primes[x]]
    x = x+1
  return primes
 
>>> sum(sieve(2000000))
142913828922L

Tags: primes, problem10, project euler, sieve of eratosthenes

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