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A050814
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Primes p such that inserting any even digit between adjacent digits produces a prime number while inserting any odd digit produces a composite number, or vice versa.
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0
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5333, 1454969, 1466833, 1790531, 1794343, 1883113, 1984459, 2179993, 2410523, 2567891, 3100301, 3259567, 3424783, 3700153, 3954131, 3972979, 4046671, 4134133, 4280033, 4544641, 4691851, 4692641, 4848523, 5006831, 5118307
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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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5333 produces five primes when an even digit is inserted (5030303, 5232323, 5434343, 5636363, 5838383) and five composites when an odd digit is inserted (5131313, 5333333, 5535353, 5737373, 5939393).
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MATHEMATICA
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a[n_, k_]:=Union[Boole/@PrimeQ[Table[FromDigits[Riffle[IntegerDigits[n], i]], {i, k+2*Range[0, 4]}]]]; t={}; Do[p=Prime[i]; x=a[p, 1]; y=a[p, 0]; If[x=={0}&&y=={1}||x=={1}&&y=={0}, AppendTo[t, p]], {i, 100, 190000}]; t (* Jayanta Basu, Jun 01 2013 *)
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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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