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A084599
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a(1) = 2, a(2) = 3; for n >= 2, a(n+1) is largest prime factor of (Product_{k=1..n} a(k)) - 1.
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3
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2, 3, 5, 29, 79, 68729, 3739, 6221191, 157170297801581, 70724343608203457341903, 46316297682014731387158877659877, 78592684042614093322289223662773, 181891012640244955605725966274974474087, 547275580337664165337990140111772164867508038795347198579326533639132704344301831464707648235639448747816483406685904347568344407941
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Like the Euclid-Mullin sequence A000946, but subtracting rather than adding 1 to the product.
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LINKS
| Dario Alpern, ECM
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EXAMPLE
| a(4)=29 since 2*3*5=30 and 29 is the largest prime factor of 30-1
a(5)=79 since 2*3*5*29=870 and 79 is the largest prime factor of 870-1=869=11*79.
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CROSSREFS
| Cf. A000946, A005265, A084598.
Essentially the same as A005266.
Sequence in context: A084598 A038962 A019400 * A062167 A107451 A093490
Adjacent sequences: A084596 A084597 A084598 * A084600 A084601 A084602
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KEYWORD
| nonn
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AUTHOR
| Marc LeBrun (mlb(AT)well.com), May 31 2003
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EXTENSIONS
| More terms from Hugo Pfoertner (hugo(AT)pfoertner.org), May 31, 2003, using Dario Alpern's ECM.
The next term a(15) is not known. It requires the factorization of the 245-digit composite number which remains after eliminating 7 smaller factors.
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