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Search: id:A103741
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| A103741 |
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a(n) is a non-palindromic composite located between twin primes whose reverse, which is less than it, is also located between twin primes. |
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+0
4
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| 60, 240, 270, 600, 810, 822, 2130, 2340, 2802, 8010, 8220, 8430, 8838, 8862, 20550, 22740, 23202, 23370, 23910, 25410, 26880, 27240, 28410, 28572, 28662, 29022, 29760, 80472, 81702, 81930, 81972, 82140, 82530, 83220, 83340, 83640, 85620
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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810 is in the sequence as it is between the twin primes 809 and 811 and its reverse, 018 or 18, is also between the twin primes 17 and 19.
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MATHEMATICA
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fQ[n_] := Block[{np = FromDigits[ Reverse[ IntegerDigits[n]]]}, If[np < n && PrimeQ[n - 1] && PrimeQ[n + 1] && PrimeQ[np - 1] && PrimeQ[np + 1], True, False]]; Select[ Range[2, 87220, 2], fQ[ # ] &] (from Robert G. Wilson v Mar 30 2005)
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CROSSREFS
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Sequence in context: A126248 A068628 A075287 this_sequence A140873 A019285 A008428
Adjacent sequences: A103738 A103739 A103740 this_sequence A103742 A103743 A103744
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KEYWORD
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base,nonn
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AUTHOR
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Ray G. Opao (1260(AT)email.com), Mar 28 2005
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EXTENSIONS
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Corrected and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Mar 30 2005
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