A prime conjecture of Mridul K. Sen

If m (> 2) and n (> 2) are positive integers, the Lucas strong base 2 pseudoprimes in the interval [m,n] are acted on by the 3x+1 mapping. Mridul K. Sen noticed that an odd prime iterate will usually be reached. We call an odd prime p 3x+1-exceptional if all its iterates are composite, apart from 2. M. K. Sen asks if there are infinitely many exceptional 3x+1 primes.

There are twenty 3x+1-exceptional primes < 1000000: 5, 113, 227, 2417, 3637, 7253, 14549, 14563, 30559, 38677, 38833, 155333, 206923, 207121, 217309, 464213, 466033, 620771, 827693, 915737.

E=1 is verbose.

Enter m (> 2):
Enter n (> 2):
Enter E (0 or 1):

Last modified 11th August 2010
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