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Search: id:A102640
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| A102640 |
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Compute the greatest prime divisors [A006530(),GPD] of j+2^n for j=0,1,...,L. a(n) is the maximal L length of such a sequence in which the greatest prime divisors are increasing with increasing j. |
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5
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| 2, 2, 4, 2, 3, 2, 2, 2, 3, 2, 2, 4, 2, 3, 2, 2, 3, 4, 2, 3, 3, 6, 2, 3, 2, 4, 2, 2, 3, 4, 2, 3, 3, 2, 2, 4, 2, 4, 2, 2, 2, 4, 2, 3, 4, 4, 2, 4, 2, 3, 3, 2, 2, 3, 2, 2, 3, 2, 2, 2, 2, 3, 2, 2, 3, 4, 2, 3, 4, 4, 2, 4, 2, 3, 2, 2, 4, 4, 2, 3, 3, 4, 2, 2, 2, 3, 2, 4, 2, 3, 2, 2, 3, 2, 2, 2, 3, 4, 2, 4, 2, 3, 2, 2, 3
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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A006530(2^n)=2 is a local minimum. Going either upward or downward with the argument, the largest prime factors are increasing for a while.
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EXAMPLE
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n=12: 2^10=4096. The greatest prime divisors for 4096, 4097, 4098, 4099 are as follows:{2, 241, 683, 4099}. A006530[4100]=41 is already smaller than A006530[4099]. Thus the length of increasing GPD-sequence is 4=a(12).
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CROSSREFS
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Cf. A006530, A102641, A102642, A102643, A102644.
Sequence in context: A113334 A127796 A131287 this_sequence A123674 A092607 A057939
Adjacent sequences: A102637 A102638 A102639 this_sequence A102641 A102642 A102643
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Jan 21 2005
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