73 -> 2n+1 ever prime?

[Christian G.Bower]

I was looking at the EIS and found sequence A051914 where Neil was
seeking clarification. So I worked out what its meaning and that led
to the following computation.

Take 73 then iterate f(n)=2n+1 on the value to get

147 295 591 1183 ...

until I get a value that's prime.

So far I'm up to

6759445072655425996692042351312808965908688011263

without finding one.

Perhaps someone with a smart prime testing algorithm can do the search
or someone with some theoretical knowledge can tell me the search is
in vain.

Christian


____________________________________________________________________
Get free email and a permanent address at http://www.netaddress.com/?N=1