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A102499
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Primes of the concatenated form 3nn3.
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3
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313133, 323233, 328283, 329293, 338383, 343433, 349493, 350503, 352523, 356563, 364643, 367673, 380803, 383833, 392923, 394943, 395953, 397973, 3100010003, 3100310033, 3102410243, 3102510253, 3102810283, 3103910393, 3104610463
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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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313133 is prime and of the form 3nn3 for n=13.
3100010003 is prime and of the form 3nn3 for n=1000.
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MATHEMATICA
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mn[n_]:=Module[{idn=IntegerDigits[n]}, FromDigits[Join[{3}, idn, idn, {3}]]]; Select[ mn/@ Range[ 1100], PrimeQ] (* Harvey P. Dale, Feb 04 2011 *)
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CROSSREFS
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Cf. A102896 for sequence of all numbers of form 3nn3. A102498 for the n values corresponding to the primes in this sequence.
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KEYWORD
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easy,nonn,base
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AUTHOR
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Mark Hudson (mrmarkhudson(AT)hotmail.com), Jan 13 2005
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STATUS
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approved
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