|
|
|
|
#15 by Joerg Arndt at Sun Oct 20 01:55:54 EDT 2019
|
|
|
|
#14 by Jon E. Schoenfield at Sat Oct 19 23:46:48 EDT 2019
|
|
|
|
#13 by Jon E. Schoenfield at Sat Oct 19 23:46:46 EDT 2019
|
| NAME
|
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).
|
| STATUS
|
approved
editing
|
|
|
|
#12 by Alois P. Heinz at Thu May 21 17:41:52 EDT 2015
|
|
|
|
#11 by Alois P. Heinz at Thu May 21 17:41:39 EDT 2015
|
| COMMENTS
|
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)
|
| EXTENSIONS
|
a(26)..)-a(32) corrected by Ivan Neretin, May 21 2015
|
| STATUS
|
proposed
editing
|
|
|
|
#10 by Ivan Neretin at Thu May 21 17:36:52 EDT 2015
|
|
|
|
#9 by Ivan Neretin at Thu May 21 17:36:28 EDT 2015
|
| EXTENSIONS
|
a(26)..a(32) corrected by Ivan Neretin, May 21 2015
|
|
|
|
#8 by Charles R Greathouse IV at Thu May 21 17:27:18 EDT 2015
|
| PROG
|
(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
|
| STATUS
|
proposed
editing
|
|
|
Discussion
|
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?
|
|
|
|
#7 by Ivan Neretin at Thu May 21 17:24:32 EDT 2015
|
|
|
|
#6 by Ivan Neretin at Thu May 21 17:22:56 EDT 2015
|
| LINKS
|
Ivan Neretin, <a href="/A068629/b068629.txt">Table of n, a(n) for n = 1..1000</a>
|
|
|
Discussion
|
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.
|
|
|
|