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A180530
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Primes that become a different prime under the mapping 1 <=> 7.
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1
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13, 17, 19, 31, 37, 41, 47, 61, 67, 71, 73, 79, 107, 109, 113, 139, 151, 157, 167, 179, 181, 191, 211, 251, 257, 277, 313, 331, 337, 373, 419, 461, 467, 479, 541, 547, 601, 607, 613, 641, 647, 673, 701, 709, 719, 739, 751, 757, 761, 773, 787, 797, 811, 821
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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, 1] || MemberQ[id, 7]) && PrimeQ[ FromDigits[ id /. {1 -> 7, 7 -> 1}] ]]; Select[ Prime@ Range@ 150, 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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