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A181493
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Numbers of the form 3*2^k which are the average of twin primes, i.e., a(n)-1 and a(n)+1 are both prime.
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6
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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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FORMULA
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MATHEMATICA
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Select[3 2^Range[500], PrimeQ[#-1]&&PrimeQ[#+1]&] (* Harvey P. Dale, Jan 18 2011 *)
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PROG
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(PARI) for( k=1, 999, ispseudoprime(3<<k-1)|next; ispseudoprime(3<<k+1)|next; print1(3<<k, ", "))
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CROSSREFS
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KEYWORD
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nonn,bref,more
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AUTHOR
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STATUS
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approved
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