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A124985
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Primes of the form 8k+7 generated recursively. Initial prime is 7. General term is min{p is prime; p divides 8Q^2-1; p == 7 (mod 8)}, where Q is the product of the previous terms.
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0
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7, 23, 207367, 1902391, 167, 1511, 28031, 79, 3142977463, 2473230126937097422987916357409859838765327, 2499581669222318172005765848188928913768594409919797075052820591, 223
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OFFSET
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1,1
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COMMENTS
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8Q^2-1 always has a prime divisor congruent to 7 modulo 8.
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REFERENCES
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D. M. Burton, Elementary Number Theory, McGraw-Hill, Sixth Edition (2007), p. 182.
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LINKS
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Table of n, a(n) for n=1..12.
N. Hobson, Home page (listed in lieu of email address)
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EXAMPLE
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a(4) = 1902391 is the smallest prime divisor, congruent to 7 modulo 8, of 8Q^2-1 = 8917046441372551 = 97 * 1902391 * 48322513, where Q = 7 * 23 * 207367.
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CROSSREFS
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Cf. A000945, A007522, A057204-A057208, A051308-A051335, A124984-A124993, A125037-A125045.
Sequence in context: A009047 A129662 A012482 * A126612 A196113 A070410
Adjacent sequences: A124982 A124983 A124984 * A124986 A124987 A124988
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KEYWORD
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nonn
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AUTHOR
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Nick Hobson Nov 18 2006
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EXTENSIONS
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Edited and added a(11)-a(12) by Max Alekseyev, May 31 2013
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STATUS
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approved
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