# Re: A prime number problem

*From*: Phil Carmody <thefatphil_demunged@xxxxxxxxxxx>*Date*: 31 Jan 2012 22:11:17 +0200

Risto Kauppila <risto.kauppila0@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> writes:

Let A = {2,3,13,23,37}

If (a_1,a_2,a_3,a_4,a_5)

is any permutation of A,

sums

a_1 + a_2*a_3*a_4*a_5

...

a_1*a_2*a_3*a_4 + a_5

are all primes.

Can you find a set of six

or more primes satisfying

the same property.

A trickier one is to find sets s.t. for any subset, the product

of the subset plus the product of its complement is prime.

Phil

--

Unix is simple. It just takes a genius to understand its simplicity

-- Dennis Ritchie (1941-2011), Unix Co-Creator

.

**References**:**A prime number problem***From:*Risto Kauppila

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