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A222960
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Numbers n such that 2*n + {3, 5, 9, 11} are all primes.
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1
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1, 4, 49, 94, 409, 739, 934, 1039, 1624, 1729, 2824, 4714, 6499, 7819, 7864, 8029, 9019, 9454, 9709, 10504, 11134, 12649, 15859, 17419, 21889, 25669, 27664, 31489, 33604, 34744, 36109, 38629, 39844, 40519, 41359, 44404
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OFFSET
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1,2
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COMMENTS
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After 1, a(n) is congruent to 4 or 9 (mod 10), this means that a(n) is of the form 5k-1. Clearly, each term is not divisible by 3 and 11.
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LINKS
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FORMULA
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MATHEMATICA
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Select[Range[50000], Union[PrimeQ[2 # + {3, 5, 9, 11}]]=={True}&]
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PROG
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(Magma) [n: n in [1..50000] | forall{2*n+k: k in [3, 5, 9, 11] | IsPrime(2*n+k)}];
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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