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Search: id:A130420
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| A130420 |
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a(n) = n-th positive integer which is coprime to n!!, where n!! = n*(n-2)*(n-4)..*(2 or 1). |
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+0
2
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| 1, 3, 4, 7, 8, 17, 16, 23, 19, 37, 29, 43, 37, 59, 41, 67, 53, 73, 62, 83, 67, 101, 79, 107, 83, 127, 89, 137, 103, 149, 113, 157, 122, 173, 128, 181, 139, 197, 146, 211, 158, 227, 173, 233, 179, 251, 194, 263, 199, 271, 206, 281, 223, 293, 227, 311, 233, 331, 251
(list; graph; listen)
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OFFSET
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1,2
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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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3!! = 3; the first number coprime to 3 is 1, the second one is 2, the third one is 4. Thus a(3) = 4.
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MATHEMATICA
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a[n_] := Module[{in}, in = 0; k = 0; While[in != n, k++; If[GCD[n!!, k] == 1, in++ ]]; k]; Table[a[i], {i, 1, 80}] - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), May 30 2007
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CROSSREFS
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Cf. A130419, A119992.
Sequence in context: A037013 A050069 A117587 this_sequence A101715 A075773 A087276
Adjacent sequences: A130417 A130418 A130419 this_sequence A130421 A130422 A130423
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KEYWORD
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less,nonn
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AUTHOR
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Leroy Quet May 25 2007
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EXTENSIONS
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More terms from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), May 30 2007
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