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Search: id:A135545
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| A135545 |
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a(n) = the largest proper divisor k of n where (k-1) and/or (k+1) divides (n+1). |
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+0
1
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| 1, 2, 1, 2, 1, 4, 3, 2, 1, 2, 1, 2, 5, 2, 1, 2, 1, 4, 3, 2, 1, 6, 1, 2, 3, 2, 1, 2, 1, 4, 3, 2, 7, 2, 1, 2, 3, 2, 1, 2, 1, 4, 3, 2, 1, 8, 1, 2, 3, 2, 1, 6, 5, 4, 3, 2, 1, 2, 1, 2, 9, 4, 5, 2, 1, 4, 3, 2, 1, 2, 1, 2, 5, 2, 7, 2, 1, 10, 3, 2, 1, 6, 1, 2, 3, 2, 1, 6, 1, 4, 3, 2, 5, 2, 1, 2, 11, 2
(list; graph; listen)
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OFFSET
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3,2
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LINKS
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Leroy Quet, Home Page (listed in lieu of email address)
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EXAMPLE
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The proper divisors of 14 are 1,2,7. Now 2 is the largest of these divisors k where (k-1) and/or (k+1) divides 15 -- both (2-1) and (2+1) divide 15. So a(14) = 2.
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MATHEMATICA
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Table[Max[Join[{1}, Select[Complement[Divisors[n], {1, n}], Mod[n + 1, # + 1] == 0 || Mod[n + 1, # - 1] == 0 &]]], {n, 3, 100}] [From Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Aug 30 2008]
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CROSSREFS
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Sequence in context: A002331 A060805 A030767 this_sequence A123317 A164879 A009195
Adjacent sequences: A135542 A135543 A135544 this_sequence A135546 A135547 A135548
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet, May 10 2008
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EXTENSIONS
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More terms from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Aug 30 2008
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