Seriously disagreement

franktaw at franktaw at
Wed Sep 3 00:31:28 CEST 2008

A closer look at this web page shows that this is counting the number 
distinct prime divisors of numbers of the form 2x^2-1 for x <= 10^n, 
the number of primes.

Note that there can be at most one prime divisor of 2x^2-1 that does
not divide 2y^2-1 for some y < x.  Every prime divisor p except 
one must be < 2x (in fact, p < sqrt(2) x), at which point p divides
2 |x-p|^2 - 1.

Franklin T. Adams-Watters

-----Original Message-----
From: Artur <grafix at>

Dear Seqfans, 

On www page 
we can read that number of primes of the form 2x^2-1 for x equal or 
than 10^n is 

8, 84, 815, 7922, 77250, 759077, 7492588, 74198995, 736401956, 
7319543971, 72834161467 


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