HS08PAUL - A conjecture of Paul Erdős

[whiterose000]

I know Sieve of Eratosthenes but I am not able to solve this problem. How can I solve this problem using Sieve.

SPOJ.com - Problem HS08PAUL

[simes]

1. Prime sieve.
2. Use a similar idea for Erdos Sieve.
3. Count them.