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A163561
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Composite numbers such that exactly nine distinct permutations of digits give primes.
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3
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1094, 1349, 1394, 1457, 1475, 1490, 1547, 1574, 1745, 1754, 1904, 1934, 1940, 1943, 3097, 3149, 3194, 3419, 3479, 3497, 3679, 3749, 3790, 3794, 3796, 3914, 3941, 3970, 3974, 3976, 4109, 4175, 4190, 4193, 4319, 4379, 4571, 4715, 4739, 4901, 4910, 4913
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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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a(1) = 1094 because 1094 is composite, the nine permutations 149, 419, 491, 941, 1049, 1409, 4019, 4091, and 9041 are all prime, and no other permutation of 1094 is prime.
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CROSSREFS
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KEYWORD
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easy,nonn,base
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AUTHOR
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STATUS
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approved
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