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A050712
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Inserting a digit '2' between adjacent digits of n makes a prime.
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10
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17, 23, 27, 29, 41, 51, 53, 77, 81, 83, 87, 89, 99, 127, 133, 139, 141, 157, 171, 181, 183, 189, 193, 207, 213, 219, 229, 261, 271, 277, 291, 307, 309, 331, 333, 337, 343, 349, 361, 403, 421, 423, 427, 433, 477, 481, 489, 493, 499, 501, 507, 511, 517, 523
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OFFSET
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1,1
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LINKS
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EXAMPLE
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333 becomes 3(2)3(2)3 which is prime 32323.
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MATHEMATICA
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Select[Range[10, 600], PrimeQ[FromDigits[Riffle[IntegerDigits[#], 2]]]&] (* Harvey P. Dale, Sep 13 2014 *)
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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