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A180548
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Primes that become a different prime under the mapping 4 <=> 7.
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1
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41, 43, 71, 73, 149, 179, 241, 271, 349, 379, 401, 409, 419, 433, 439, 443, 461, 541, 571, 643, 673, 701, 709, 719, 733, 739, 761, 773, 941, 971, 1249, 1279, 1409, 1423, 1433, 1453, 1459, 1471, 1483, 1489, 1549, 1579, 1709, 1723, 1733, 1741, 1753, 1759
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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, 4] || MemberQ[id, 7]) && PrimeQ[ FromDigits[ id /. {4 -> 7, 7 -> 4}] ]]; Select[ Prime@ Range@ 300, 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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