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5
9th November 21:40
External User
Posts: 1

Primes and the Collatz conjecture!
It is not a prime: it is 8191 * 2731. More generally, 2^(2j)1 is
always divisible by 2^j1, so (2^(2j)1)/3 is never prime for j >= 3. Of course what this means is that if the sequence starting at k gets to 1, and all odd numbers in the path until 1 are prime, the last part of the path must be 5 > 16 > 8 > 4 > 2 > 1. Robert Israel israel@math.ubc.ca Department of Mathematics http://www.math.ubc.ca/~israel University of British Columbia Vancouver, BC, Canada V6T 1Z2 