2007 fun

[Nick Hobson]

The simple PARI/GP script below found that 20071*(10^n) + (10^n)\3 is  
prime for n = number of 3s =

1, 2, 3, 4, 5, 6, 26, 73, 87, 220, 248, ...

... before I cancelled it after about 10 minutes.

for(n=1, 500, x=20071*(10^n) + (10^n)\3; if(isprime(x), print1(n, ", ")))

Nick


On Wed, 03 Jan 2007 16:37:48 -0000, Ed Pegg Jr <edp at wolfram.com> wrote:

> 2007 isn't prime, since it's divisible by 9.
> 20071 is prime
> 200713 is prime. 2007133 is prime
> 20071333 is prime
> 200713333 is prime
> 2007133333 is prime
> 20071333333 is prime
> But it stops there.
>
> --Ed Pegg Jr
>
>