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A057208
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Primes of form 8k+5 generated recursively: a(1)=5, a(n) = least prime p = 5 mod 8 with p|4+Q^2, where Q is the product of all previous terms in the sequence.
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24
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OFFSET
| 1,1
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REFERENCES
| Dirichlet,P.G.L (1871):Vorlesungen uber Zahlentheorie. Braunschweig,Viewig,Supplement VI, 24 pages.
G. H. Hardy and E. M. Wright, An Introduction to the Theory of Numbers. 3rd ed., Oxford Univ. Press, 1954, page 13.
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EXAMPLE
| a(3)=1237=8*154+5 is the smallest suitable prime divisor of (5.29)*5.29+4=21029=17*1237. Albeit 17 is the smallest prime divisor, but 17 is not congruent to 5 modulo 8, so 1237 is the good choice.
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CROSSREFS
| Cf. A000945, A000946, A005265, A005266, A051308-A051335, A007521, A057204-A057208.
Sequence in context: A072880 A112959 A085553 * A046842 A175905 A057706
Adjacent sequences: A057205 A057206 A057207 * A057209 A057210 A057211
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Oct 09 2000
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