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Search: id:A124740
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| A124740 |
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a(n) = product of those positive integers which are coprime to both n and n+1 and which are <= n. |
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+0
6
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| 1, 1, 1, 3, 1, 5, 15, 35, 7, 189, 35, 385, 1485, 143, 1001, 2027025, 5005, 85085, 459459, 46189, 20995, 1249937325, 1616615, 7436429, 324342711, 71504125, 132793375, 1452095555625, 7436429, 215656441, 6190283353629375, 75969882625
(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. The integers in both these sequences (1,5,7) are multiplied to get a(8) = 35.
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MATHEMATICA
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f[n_] := Times @@ Select[Range[n], GCD[n, # ] == GCD[n + 1, # ] == 1 &]; Table[f[n], {n, 33}] (*Chandler*)
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CROSSREFS
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Cf. A057475, A124738, A124739, A124741.
Sequence in context: A091623 A059616 A125053 this_sequence A073597 A104053 A039512
Adjacent sequences: A124737 A124738 A124739 this_sequence A124741 A124742 A124743
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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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