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Search: id:A124741
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| A124741 |
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a(n) = largest of those positive integers which are coprime to both n and n+1 and which are <= n. |
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+0
5
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| 1, 1, 1, 3, 1, 5, 5, 7, 7, 9, 7, 11, 11, 13, 13, 15, 13, 17, 17, 19, 19, 21, 19, 23, 23, 25, 25, 27, 23, 29, 29, 31, 31, 33, 31, 35, 35, 37, 37, 39, 37, 41, 41, 43, 43, 45, 43, 47, 47, 49, 49, 51, 49, 53, 53, 55, 55, 57, 53, 59, 59, 61, 61, 63, 61, 65, 65, 67, 67, 69, 67, 71, 71
(list; graph; listen)
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OFFSET
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1,4
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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 positive integers which are coprime to 8 and which are <= 8 are 1,3,5,7. The positive integers which are coprime to 9 and which are <= 9 are 1, 2,4,5,7,8. So a(8) = 7, which is the largest of those integers in both these sequences (1,5,7).
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MATHEMATICA
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f[n_] := Last @ Select[Range[n], GCD[n, # ] == GCD[n + 1, # ] == 1 &]; Table[f[n], {n, 75}] (*Chandler*)
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CROSSREFS
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Cf. A057475, A124738, A124739, A124740.
Sequence in context: A104489 A067285 A067286 this_sequence A146913 A146252 A049266
Adjacent sequences: A124738 A124739 A124740 this_sequence A124742 A124743 A124744
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet Nov 06 2006
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EXTENSIONS
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Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Nov 10 2006
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