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.
Each week, for your edification, we publish a well-known unsolved mathematics problem. These postings are intended to inform you of some of the difficult, yet interesting, problems that mathematicians are investigating. We do not suggest that you tackle these problems, since mathematicians have been unsuccessfully working on these problems for many years. general references
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