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A302350
Instance of a permutation of the positive integers such that lcm(a(n), a(n+1)) <= c*n*log(n)^2.
8
1, 6, 3, 15, 30, 10, 5, 20, 2, 140, 35, 70, 210, 105, 21, 42, 14, 7, 77, 154, 770, 385, 55, 110, 330, 165, 33, 66, 22, 11, 143, 429, 858, 286, 2002, 91, 273, 546, 182, 910, 455, 65, 130, 390, 195, 39, 78, 26, 13, 221, 663, 1326, 442, 4862, 187, 561, 1122, 374, 2618, 119, 357, 714, 238, 1190, 595, 85, 170, 510, 255, 51, 102, 34, 17
OFFSET
1,2
COMMENTS
For details of the construction see [Mazet & Saias].
This sequence is also a "chain": a(n) is either a divisor or a multiple of a(n+1).
Another instance of a "permutation-chain" is: A064736.
LINKS
Michel Marcus, Table of n, a(n) for n = 1..5168 (for 26 iterations)
Y.-G. Chen and C.-S. Ji, The permutation of integers with small least common multiple of two subsequent terms, Acta Math. Hungarica 132(2011), 307-309.
P. Erdős, R. Freud, and N. Hegyvári, Arithmetical properties of permutations of integers, Acta Mathematica Hungarica 41:1-2 (1983), pp 169-176.
Michel Marcus, PARI scripts
Pierre Mazet, Eric Saias, Etude du graphe divisoriel 4, arXiv:1803.10073 [math.NT], 2018.
G. Tenenbaum, Sur un problème de crible et ses applications, Annales scientifiques de l'École Normale Supérieure, 4ème série, tome 19, n°1, (1986), p.1-30.
G. Tenenbaum, Sur un problème de crible et ses applications. II. Corrigendum et étude du graphe divisoriel, Annales scientifiques de l'École Normale Supérieure, Série 4 : Tome 28 (1995) no. 2 , p. 115-127.
PROG
(PARI) See links.
CROSSREFS
Cf. A064736.
Sequence in context: A362625 A352015 A225503 * A046879 A248267 A236415
KEYWORD
nonn
AUTHOR
Michel Marcus, Apr 06 2018
STATUS
approved