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Search: id:A047811
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| A047811 |
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Numbers n which are not palindromic in any base b, 2<=b<=n/2. |
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+0
8
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| 4, 6, 11, 19, 47, 53, 79, 103, 137, 139, 149, 163, 167, 179, 223, 263, 269, 283, 293, 311, 317, 347, 359, 367, 389, 439, 491, 563, 569, 593, 607, 659, 739, 827, 853, 877, 977, 983, 997, 1019, 1049, 1061, 1187, 1213, 1237, 1367, 1433, 1439, 1447, 1459
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Note that no prime p is palindromic in base b for the range sqrt(p) < b < p-1. Hence to find non-palindromic primes, we need only examine bases up to floor(sqrt(p)), which greatly reduces the computational effort required. - T. D. Noe, Mar 01 2008
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REFERENCES
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R. K. Guy, Conway's RATS and other reversals, Amer. Math. Monthly, 96 (1989), 425-428.
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..10000
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CROSSREFS
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Cf. A033868, A050812, A050813, A016038.
Cf. A135549
Adjacent sequences: A047808 A047809 A047810 this_sequence A047812 A047813 A047814
Sequence in context: A060577 A058579 A022318 this_sequence A091280 A066155 A105308
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KEYWORD
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nonn,base,easy,nice
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AUTHOR
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njas
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EXTENSIONS
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Extended (and corrected) by Patrick De Geest (pdg(AT)worldofnumbers.com), Oct 15 1999.
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