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A155507
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Emirps with digits 1 and 9 only.
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3
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199, 991, 91199, 99119, 111119, 111919, 119191, 191911, 911111, 919111, 991999, 999199, 1191119, 1191191, 1191991, 1911911, 1991911, 9111911, 11111911, 11191991, 11911111, 11919991, 19111991, 19911191, 19919111, 19991911
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listen;
history;
text;
internal format)
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OFFSET
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1,1
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COMMENTS
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LINKS
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MATHEMATICA
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emrpQ[n_]:=Module[{r=IntegerReverse[n]}, r!=n&&AllTrue[{r, n}, PrimeQ]]; Table[Select[FromDigits/@Tuples[{1, 9}, n], emrpQ], {n, 8}]//Flatten (* Harvey P. Dale, Aug 09 2017 *)
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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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