And incidentally every other power of 2 is 3*an odd number +1 and the others are 3*and odd number minus 1. ]]>

[*The two constraints are logically equivalent, since is never divisible by 3. -T.]*

There are infinity of algorithms in the form for the cycle 4,2,1.

The first with $latex(X = 3)$; the second ; the third .

See:

]]>This is the URL that points to the paper, but it cannot be accessed:

http://www.ams.org/mathscinet-getitem?mr=551509

Thank you!!

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