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A180559
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Primes that become a different prime under the mapping 7 <=> 9.
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46
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17, 19, 79, 97, 107, 109, 137, 139, 173, 179, 193, 197, 227, 229, 347, 349, 379, 397, 577, 599, 617, 619, 709, 727, 739, 769, 827, 829, 857, 859, 907, 929, 937, 967, 1279, 1297, 1427, 1429, 1487, 1489, 1579, 1597, 1607, 1609, 1667, 1669, 1709, 1733, 1747
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listen;
history;
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internal format)
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OFFSET
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1,1
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LINKS
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MATHEMATICA
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fQ[n_] := Block[{id = IntegerDigits@n}, (MemberQ[id, 7] || MemberQ[id, 9]) && PrimeQ[ FromDigits[ id /. {7 -> 9, 9 -> 7}] ]]; Select[ Prime@ Range@ 275, fQ]
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CROSSREFS
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KEYWORD
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base,nonn
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AUTHOR
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STATUS
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approved
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