language: Python (python 2.7.3)
date: 363 days 10 hours ago
link:
visibility: public 
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def primes(N):
 return reduce((lambda r,x: r-set(range(x**2,N,x)) if (x in r) else r), 
               range(2,N), set(range(2,N)))
 
print( sorted( list( primes( 10000)))[-2:] )
 
# 10k:  time: 0.14s    memory: 5112 kB
# 20k:  time: 0.50s    memory: 5204 kB 
# 40k:  time: 1.44s    memory: 5708 kB
# 100k: time: 10.46s   memory: 7124 kB     n^2.2
set-based one-liner