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A319535
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Primes of the form 2*6^k - 1.
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1
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11, 71, 431, 2591, 15551, 4353564671, 5642219814911, 341163456359156416511, 2046980738154938499071, 20628849596981071092343898111, 26734989077687468135677691953151, 207891275068097752223029732627709951, 269427092488254686881046533485512097791
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OFFSET
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1,1
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COMMENTS
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Companion sequence of A057472. There are 49 terms known in this sequence.
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LINKS
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FORMULA
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EXAMPLE
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2*6^1 - 1 = 11, 2*6^2 - 1 = 71, 2*6^3 - 1 = 431, 2*6^4 - 1 = 2591 and 2*6^5 - 1 = 15551 are primes, but 2*6^6 - 1 = 93311 = 23*4057 is not.
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MAPLE
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MATHEMATICA
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Select[Table[2*6^k-1, {k, 1600}], PrimeQ[#]&] (* K. D. Bajpai, Nov 15 2019 *)
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PROG
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(PARI) for(n=1, 99, my(t); if(ispseudoprime(t=2*6^n-1), print1(t", ")))
(Magma) [k: n in [1..100] | IsPrime(k) where k is 2*6^n-1]; // K. D. Bajpai, Nov 15 2019
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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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