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Search: id:A088883
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| A088883 |
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Primes which when concatenated with their reverse and incremented by 2 yield a new prime. |
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+0
2
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| 7, 19, 97, 109, 151, 163, 181, 193, 547, 709, 727, 733, 991, 1039, 1093, 1279, 1447, 1453, 1567, 1621, 1657, 1669, 1699, 1723, 1867, 5077, 5179, 5209, 5281, 5323, 5419, 5503, 5563, 5581, 5653, 5821, 5857, 5881, 7057, 7207, 7219, 7333, 7351, 7507, 7537
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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It appears that if concat(p,reverse(p))+2 is prime, then concat(p,reverse(p))-2 is not and vice versa. This was tested for the first 60000 primes.
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EXAMPLE
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a(4) =109 because (i) 109 is prime and (ii) when 109 is concatenated with its reverse (901) + 2, the result (109903) is prime.
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CROSSREFS
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Cf. A067087 (concatenation of n-th prime and its reverse.), A088884 (primes which when concatenated with their reverse and decremented by 2 yield a new prime.).
Sequence in context: A109879 A109880 A084603 this_sequence A026574 A091149 A070976
Adjacent sequences: A088880 A088881 A088882 this_sequence A088884 A088885 A088886
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KEYWORD
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base,nonn
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AUTHOR
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Chuck Seggelin (barkeep(AT)plastereddragon.com), Oct 21 2003
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