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Search: id:A083388
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| A083388 |
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a(n) = beginning of a run of n primes when x -> 3*x + 2 is iterated. |
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+0
9
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| 2, 3, 5, 29, 1129, 10009, 575119, 32694619, 586130089, 1030544269
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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a(11) > 8695354111. [From Donovan Johnson (donovan.johnson(AT)yahoo.com), Sep 27 2008]
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REFERENCES
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D. H. Lehmer, On certain chains of primes, Proc. London Math. Soc. (3) 14a 1965 183-186.
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EXAMPLE
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a(3) = 5 because 5 is the beginning of 3 primes in succession: 5, 3*5+2=17 is prime and 3*17+2=53 is prime.
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PROGRAM
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(PARI) mx=1; forprime(p=1, 198000, x=p; m=0; while(isprime(x=3*x+2), m=m+1; if(m>mx, print(p, " ", m, " ", x); mx=m, )))
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CROSSREFS
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Cf. A057331, A081173.
Sequence in context: A093490 A073309 A110389 this_sequence A090475 A060301 A040119
Adjacent sequences: A083385 A083386 A083387 this_sequence A083389 A083390 A083391
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KEYWORD
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nonn
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AUTHOR
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Edwin Clark (eclark(AT)math.usf.edu), Jun 09 2003
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EXTENSIONS
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PARI program from Donald S. McDonald (don.mcdonald(AT)paradise.net.nz), Jun 11 2003
a(8)-a(10) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Sep 27 2008
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