prime number questions

**sah_mat** · November 22nd 2008, 05:54 AM

1)if p is bigger than 3 and prime,than prove $p^2+p$ is prime.
2) $\forall{n}\in{N},2^{2^n}+1$ is prime prove.

**Opalg** · November 22nd 2008, 06:06 AM

$p^2+p$ is never prime, because it factorises as $p(p+1)$ .

$2^{2^5}+1 = 4294967297 = 641\times 6700417$ , so that is not prime either. It is not known whether there is any value of n greater than 4 for which the Fermat number $2^{2^n}+1$ is prime.

**sah_mat** · November 22nd 2008, 08:56 AM

if p and ${2^p}-1$ is prime then prove $2^{p-1}(2^p-{1})$ is a perfect number.

thanks fpr your helping,opalg

**o_O** · November 22nd 2008, 09:03 AM

Already done: Perfect Numbers

For separate questions, please make new threads.

**sah_mat** · November 22nd 2008, 09:09 AM

ı am sorry guys ı am new on the site ı will be carefull

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