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Topic: Status of palindrome conjecture?
Replies: 5   Last Post: Jun 17, 1996 5:58 PM

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Kurt Foster

Posts: 114
Registered: 12/12/04
Status of palindrome conjecture?
Posted: Jun 17, 1996 11:04 AM
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There's an old conjecture that, if you take a positive integer, and
repeatedly reverse the digits and add the two mirror image numbers, you
eventually get a palindrome. An article in Scientific American many years
ago said this conjecture had never been proved true in any base, but had
been proved false in the binary; the article gave the first known binary
counterexample and sketched the proof that it was such.
The first possible counterexample in base ten was given as 196, for
which the process had been carried through tens of thousands of iterations
without encountering a palindrome. Someone just informed me by E-mail
that he was running the process for 196 on his computer, and had gone
through over 200,000 iterations without finding a palindrome.
If anyone has some references to this problem more recent than the
article mentioned above [which I think is about 20 years old], I'd like to
know so my correspondent's computer can take a breather!

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