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Search: id:A088884
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| A088884 |
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Primes which when concatenated with their reverse and decremented by 2 yield a new prime. |
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+0
2
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| 3, 5, 11, 53, 107, 131, 149, 167, 179, 191, 311, 317, 389, 503, 599, 947, 971, 1049, 1061, 1097, 1187, 1223, 1259, 1427, 1439, 1523, 1571, 1583, 1697, 1721, 1787, 1811, 1871, 1913, 1931, 1949, 3089, 3119, 3191, 3209, 3299, 3449, 3617, 3671, 3677, 3761
(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) =53 because (i) 53 is prime and (ii) when 53 is concatenated with its reverse (35) - 2, the result (5333) is prime.
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CROSSREFS
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Cf. A067087 (Concatenation of n-th prime and its reverse.), A088883 (Primes which when concatenated with their reverse and incremented by 2 yield a new prime.).
Sequence in context: A049883 A059242 A004203 this_sequence A058029 A046928 A089070
Adjacent sequences: A088881 A088882 A088883 this_sequence A088885 A088886 A088887
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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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