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#13 by Joerg Arndt at Thu Jun 25 01:59:00 EDT 2020
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#12 by Michel Marcus at Thu Jun 25 00:32:10 EDT 2020
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#11 by Sean A. Irvine at Wed Jun 24 23:41:46 EDT 2020
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Discussion
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| Wed Jun 24
| 23:44
| Michel Marcus: or maybe nor ?
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| 23:48
| Sean A. Irvine: I think the important point is that both a prefix and suffix are required.
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#10 by Sean A. Irvine at Wed Jun 24 23:40:29 EDT 2020
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| NAME
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Palindromes that cannot be prefixed orand followed by any digit to form a prime.
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| EXAMPLE
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11111 prefixed orand followed with a digit from (1,2,3,4,5,6,7,8,9) never yields a prime: '2'11111'3' = 29 x 72797.
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| STATUS
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approved
editing
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Discussion
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| Wed Jun 24
| 23:41
| Sean A. Irvine: I think "and" rather than "or" is the right connective here. Note that 11111'9' is prime, so this sequence requires adding a digit at both ends.
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#9 by Michel Marcus at Thu Nov 12 03:26:00 EST 2015
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#8 by Joerg Arndt at Thu Nov 12 01:56:08 EST 2015
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#7 by Chai Wah Wu at Wed Nov 11 20:03:08 EST 2015
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#6 by Chai Wah Wu at Wed Nov 11 20:02:48 EST 2015
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| LINKS
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Chai Wah Wu, <a href="/A032735/b032735.txt">Table of n, a(n) for n = 1..10000</a>
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| STATUS
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approved
editing
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#5 by Charles R Greathouse IV at Mon Mar 09 09:35:21 EDT 2015
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Discussion
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| Mon Mar 09
| 09:35
| OEIS Server: https://oeis.org/edit/global/2362
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#4 by Charles R Greathouse IV at Fri Aug 24 10:47:48 EDT 2012
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| AUTHOR
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_Patrick De Geest (pdg(AT)worldofnumbers.com), _, May 15, 1998.
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Discussion
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| Fri Aug 24
| 10:47
| OEIS Server: https://oeis.org/edit/global/1824
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