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A012884
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Numbers such that every prefix and suffix is 1 or a prime.
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5
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1, 2, 3, 5, 7, 11, 13, 17, 23, 31, 37, 53, 71, 73, 113, 131, 137, 173, 197, 311, 313, 317, 373, 797, 1373, 1997, 3137, 3797, 7331, 73331, 739397
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OFFSET
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1,2
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COMMENTS
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LINKS
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MATHEMATICA
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prQ[n_] := n == 1 || PrimeQ[n];
okQ[n_] := Module[{dd, nd}, dd = IntegerDigits[n]; nd = Length[dd]; AllTrue[Range[nd], prQ@ FromDigits@ Take[dd, #]&] && AllTrue[Range[nd-1], prQ@ FromDigits@ Drop[dd, #]&]];
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CROSSREFS
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KEYWORD
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nonn,fini,full,nice,base
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AUTHOR
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STATUS
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approved
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