18-Jun-1995

Unsolved Problem 25:

Start with any positive integer. Halve it if it is even; triple it and add 1 if it is odd. If you keep repeating this procedure, must you eventually reach the number 1?

For example, starting with the number 6, we get: 6, 3, 10, 5, 16, 8, 4, 2, 1.

Reference:

[Gardner 1983]
Martin Gardner, Wheels, Life, and Other Mathematical Amusements. W. H. Freeman. New York: 1983. Page 196.
The Collatz Conjecture
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