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A112042
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Numbers k such that 1*k + 1, 3*k + 1, 9*k + 1, 27*k + 1, 81*k + 1 are all primes.
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2
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60, 760, 2440, 5800, 8680, 17350, 21840, 27010, 40030, 84060, 108010, 109890, 131110, 222940, 277750, 309120, 313030, 334170, 346140, 348660, 356500, 358330, 387160, 419230, 470880, 553410, 578820, 604030, 683340, 729820, 799890, 801630
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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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prQ[n_]:=Module[{ns=n*3^Range[0, 4]+1}, And@@PrimeQ[ns]]; Select[Range[ 810000], prQ] (* Harvey P. Dale, Jul 01 2012 *)
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PROG
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(Magma) [n: n in [1..1000000] |IsPrime(n+1) and IsPrime(3*n+1) and IsPrime(9*n+1) and IsPrime(27*n+1)and IsPrime(81*n+1)] // Vincenzo Librandi, Nov 13 2010
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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