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A225057
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Least prime p such that p*6^n +/- 1 are primes.
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0
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2, 2, 2, 2, 47, 3, 53, 677, 823, 227, 1907, 1103, 17, 163, 2693, 1213, 277, 2767, 887, 8353, 1013, 773, 6967, 1423, 2593, 9643, 157, 18013, 263, 2137, 2837, 107, 3467, 2137, 17, 2777, 1453, 2683, 7963, 3517, 2767, 53527, 8563, 227, 367, 27673, 30853, 5087, 7723, 14753, 41687, 137, 48647, 26357, 16747, 2797, 9887, 35933
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OFFSET
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1,1
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COMMENTS
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a(1) >= A064215(n). First n's such that a(n) = A064215(n): 2, 3, 4, 6, 13, 27, 29, 32, 35, 40, 44, 45, 52, 60, 67, 71, 79, 86, 87, 97, 99.
According to Dickson's Conjecture a(n) exists for any n.
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LINKS
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MATHEMATICA
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Table[ n6=6^n; p = 2; While[ ! PrimeQ[q = p*n6 + 1 ] || ! PrimeQ[ q - 2 ], p = NextPrime[p] ]; p, {n, 100}]
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CROSSREFS
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Cf. A064215 (least k: k*6^n +/- 1 are primes).
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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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