- Let seq(p) = 23571113171923...p
seq(2) = 2 = prime
seq(3) = 23 = prime
seq(7) = 2357 = prime
Is there any p > 7 for which seq(p) is prime? I tried up to p = 223.
- "Werner D. Sand" wrote:
>Well, I have a small archive of posts to the group before the group was
> Let seq(p) = 23571113171923...p
> seq(2) = 2 = prime
> seq(3) = 23 = prime
> seq(7) = 2357 = prime
> Is there any p > 7 for which seq(p) is prime? I tried up to p = 223.
moved to yahoo, and this was brought up before, here was the highest
that anyone on the list (at that time) came up with:
On Mon, 24 Apr 2000 Brian Schroeder wrote:
> Well, prime_cat(2,719) is prime with 355 digits and prime_cat(2,1033) > is prime with 499 digits and prime_cat(2,2297) is prime with 1171 > digits and prime_cat(2,3037) is prime with 1543 digits.
And then we got another excelent result from Marcel Martin who wrote:
On Tue, 25 Apr 2000 Marcel Martin wrote:
> Hello all,
> Sorry for my last mail. I gave the same infos than Brian Schroeder.
> I received his mail after having sent mine :(
> Well, I let my PC run all day long. All numbers from > prime_cat(2,3041) to prime_cat(2,11923) are composite.
> prime_cat(2,11927) is a strong pseudoprime for the bases 2, 3, 5,
> 7 and 11. This number has 5719 decimal digits.
> Marcel Martin
Where we defined prime_cat(x,y) to be the concatenation of all primes
from x to y, inclusively. I'd be curious to know, has anyone done any
more work on this since then?
- David Cleaver wrote:
> I'd be curious to know, has anyone done anyhttp://mathworld.wolfram.com/ConsecutiveNumberSequences.html says
> more work on this since then?
Eric Weisstein found no other prp's in the first 14897 terms.
prime(14897) = 162623 gives a number with 78364 digits.
Jens Kruse Andersen