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A119862 Smallest number not yet used that is either a divisor or multiple of both n and a(n-1). 1
1, 2, 6, 12, 60, 3, 21, 168, 504, 2520, 27720, 4, 52, 364, 5460, 21840, 371280, 1113840, 21162960, 5, 105, 2310, 53130, 212520, 1062600, 13813800, 124324200, 7, 203, 6090, 188790, 3020640, 33227040, 564859680, 35, 1260, 46620, 885780, 11515140, 10, 410 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

This is apparently the smallest divisor of gcd(n,a(n-1)) not yet used if such exists, or lcm(n,a(n-1)) otherwise. This is a permutation of the positive integers. The required lemma is that there are arbitrarily long sequences where a(n) = lcm(n,a(n-1)).

LINKS

Paul Tek, Table of n, a(n) for n = 1..10000

CROSSREFS

Sequence in context: A175810 A083001 A285079 * A111936 A232090 A203811

Adjacent sequences:  A119859 A119860 A119861 * A119863 A119864 A119865

KEYWORD

nonn

AUTHOR

Franklin T. Adams-Watters, Jul 31 2006

STATUS

approved

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Last modified October 17 05:57 EDT 2018. Contains 316275 sequences. (Running on oeis4.)