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Search: id:A005266
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| A005266 |
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a(1)=3, b(n)=Product_{k=1..n} a(k), a(n+1)=largest prime factor of b(n)-1.
(Formerly M2247)
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+0
39
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| 3, 2, 5, 29, 79, 68729, 3739, 6221191, 157170297801581, 70724343608203457341903, 46316297682014731387158877659877, 78592684042614093322289223662773, 181891012640244955605725966274974474087, 54727558033766416533799014011177216486750803879534719857932653363913270434430183\ 1464707648235639448747816483406685904347568344407941
(list; graph; listen)
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OFFSET
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0,1
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COMMENT
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Suggested by Euclid's proof that there are infinitely many primes.
a(15) requires completing the factorization: 13 * 67 * 14479 * 167197 * 924769 * 2688244927 * 888838110930755119 * 14372541055015356634061816579965403 * C211 where C211=6609133306626483634448666494646737799624640616060730302142187545405582531010390290502001156883917023202671554510633460047901459959959325342475132778791495112937562941066523907603281586796876335607258627832127303 [From Sean A. Irvine (sairvin(AT)xtra.co.nz), Nov 10 2009]
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
R. K. Guy and R. Nowakowski, Discovering primes with Euclid, Delta (Waukesha), Vol. 5, pp. 49-63, 1975.
S. S. Wagstaff, Jr., Computing Euclid's primes, Bull. Institute Combin. Applications, 8 (1993), 23-32.
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CROSSREFS
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Cf. A000945, A000946, A005265.
Essentially the same as A084599.
Sequence in context: A103938 A085973 A005265 this_sequence A005267 A016460 A097887
Adjacent sequences: A005263 A005264 A005265 this_sequence A005267 A005268 A005269
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KEYWORD
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nonn,nice,new
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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a(14) from Joe K. Crump (joecr(AT)carolina.rr.com), Jul 26, 2000
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