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Search: id:A069469
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| A069469 |
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Numbers n such that prime(reversal(n)) = reversal(prime(n)). Ignore leading 0's. |
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+0
1
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OFFSET
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1,2
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COMMENT
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1. For an arithmetical function f, call the arguments n such that f(reverse(n)) = reverse(f(n)) the "palinpoints" of f. This sequence is the sequence of palinpoints of f(n) = Prime(n). 2. These are all the palinpoints of Prime(n) not exceeding 10^5. Are there more?
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EXAMPLE
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Let f(n) = Prime(n). Then f(21) = 73, f(12) = 37, so f(reverse(21)) = reverse(f(21)). Therefore 21 belongs to the sequence.
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MATHEMATICA
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rev[n_] := FromDigits[Reverse[IntegerDigits[n]]]; f[n_] := Prime[n]; Select[Range[10^5], f[rev[ # ]] == rev[f[ # ]] &]
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CROSSREFS
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Sequence in context: A093713 A057472 A117577 this_sequence A109849 A007662 A109744
Adjacent sequences: A069466 A069467 A069468 this_sequence A069470 A069471 A069472
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KEYWORD
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base,nonn
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AUTHOR
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Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Apr 15 2002
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