Before trying the problems "note your opinion as to whether the observed pattern is known to continue, known not to continue, or not known at all."
Is 7013*2n+1 always composite?
Is 78557*2n+1 always composite?
(In reply to Does it continue?
It's an interesting question, Jer.
For my part, I freely admit I had no instinctive opinion as to the pattern in these cases.
Having looked at the forthcoming problems in the queue, without attempting to solve:
3: No reason to think so.
4: Yes, almost certainly.
5,6: Reasonably obvious.
I look forward to proving myself wrong in due course.
Meanwhile, thank you for your kind words!
Edited on September 18, 2017, 3:53 am
Posted by broll
on 2017-09-17 23:05:37