The general formula is x=(n^n1)/(n1), which gives a base 10 value that can quickly be checked for primality. Obviously, only prime n need be checked. Using this method,
{{n == 2, x == 3}
{n == 3, x == 13}
{n == 5, x == 781}
{n == 7, x == 137257}
{n == 11, x == 28531167061}
{n == 13, x == 25239592216021}
{n == 17, x == 51702516367896047761}
{n == 19, x == 109912203092239643840221}...}
109912203092239643840221 is prime, and in base 19 is:
1111111111111111111.
Edited on July 24, 2013, 11:45 am

Posted by broll
on 20130724 11:29:46 