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A269891
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Primes p such that both the concatenation and the sum of 2 and p are prime.
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1
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3, 11, 29, 41, 71, 137, 179, 239, 269, 281, 311, 347, 521, 617, 659, 857, 1019, 1031, 1061, 1277, 1319, 1481, 1487, 1787, 1871, 1997, 2027, 2111, 2129, 2381, 2549, 3167, 3251, 3371, 3539, 3557, 3581, 3671, 3767, 3917, 3929, 4001, 4019, 4049, 4091, 4229, 4337, 4421, 4481, 4517, 4547, 4799, 4967, 5639, 5657
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OFFSET
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1,1
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COMMENTS
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All terms are lesser of twin primes (A001359).
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LINKS
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EXAMPLE
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23 and 2+3=5 are primes, 211 and 2+11=13 are primes.
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MATHEMATICA
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Reap[Do[If[PrimeQ[2+(p=Prime[n])]&&PrimeQ[ToExpression["2"<>ToString[p]]], Sow[p]], {n, 10^3}]][[2, 1]]
Select[Prime@ Range@ 800, And[PrimeQ@ FromDigits[Prepend[IntegerDigits@ #, 2]], PrimeQ[# + 2]] &] (* Michael De Vlieger, Mar 07 2016 *)
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PROG
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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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STATUS
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approved
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