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A119862 Smallest number not yet used that is either a divisor or multiple of both n and a(n-1). +0
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; listen)
OFFSET

1,2

COMMENT

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)).

CROSSREFS

Sequence in context: A164859 A152873 A083001 this_sequence A111936 A002805 A117481

Adjacent sequences: A119859 A119860 A119861 this_sequence A119863 A119864 A119865

KEYWORD

nonn

AUTHOR

Frank Adams-Watters (FrankTAW(AT)Netscape.net), Jul 31 2006

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Last modified December 7 08:40 EST 2009. Contains 170430 sequences.


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