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#15 by Joerg Arndt at Sun Oct 20 01:55:54 EDT 2019
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#14 by Jon E. Schoenfield at Sat Oct 19 23:46:48 EDT 2019
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#13 by Jon E. Schoenfield at Sat Oct 19 23:46:46 EDT 2019
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| NAME
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a(1) = 1. a(n) = n*a(n-1) if GCDgcd(n,a(n-1)) = 1. a(n) = , a(n-1)/n if n divides a(n-1). else), otherwise a(n) = a(n-1).
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| STATUS
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approved
editing
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#12 by Alois P. Heinz at Thu May 21 17:41:52 EDT 2015
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#11 by Alois P. Heinz at Thu May 21 17:41:39 EDT 2015
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| COMMENTS
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The sequence can also be obtained by taking a(1) = 1 and then multiplying the previous term by n if n is coprime to the previous term a(n-1), dividing the previous term by n if n divides the previous term a(n-1), taking a(n) = a(n-1) if n is unrelated to a(n-1). - Amarnath Murthy, Oct 30 2002 (corrected by _Franklin T. Adams-Watters, _, Dec 13 2006)
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| EXTENSIONS
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a(26)..)-a(32) corrected by Ivan Neretin, May 21 2015
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| STATUS
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proposed
editing
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#10 by Ivan Neretin at Thu May 21 17:36:52 EDT 2015
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#9 by Ivan Neretin at Thu May 21 17:36:28 EDT 2015
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| EXTENSIONS
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a(26)..a(32) corrected by Ivan Neretin, May 21 2015
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#8 by Charles R Greathouse IV at Thu May 21 17:27:18 EDT 2015
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| PROG
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(PARI) print1(k=1); for(n=2, 99, if(gcd(k, n)==1, k*=n, if(k%n==0, k/=n)); print1(", "k)) \\ Charles R Greathouse IV, May 21 2015
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| STATUS
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proposed
editing
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Discussion
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| Thu May 21
| 17:28
| Charles R Greathouse IV: I concur. Ivan, would you add a note to the extensions to the effect that you corrected a(26) and on?
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#7 by Ivan Neretin at Thu May 21 17:24:32 EDT 2015
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#6 by Ivan Neretin at Thu May 21 17:22:56 EDT 2015
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| LINKS
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Ivan Neretin, <a href="/A068629/b068629.txt">Table of n, a(n) for n = 1..1000</a>
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Discussion
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| Thu May 21
| 17:24
| Ivan Neretin: There seemed to be a mistake at n=26 affecting the following terms. Indeed, a(25)=19315400 is divisible by 26, so it should be divided.
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