2 is a prime. (1 - 2)
3 is a prime. (2 - 1.5)
5 is a prime. (3 - 1.6666666666667)
7 is a prime. (4 - 1.75)

Execution time was 0.00047397613525391 seconds.

PHP version is 4.4.3-dev

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 get primes of other ones  |   debug (will only work if (last - first) <= 10)