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 A285039 Lexicographically earliest sequence of distinct terms such that, for any n>0, a(n) is divisible by k and a(n+1) is divisible by prime(k) for some k. 3
 1, 2, 3, 4, 6, 5, 8, 7, 10, 9, 12, 13, 14, 15, 11, 16, 18, 20, 21, 17, 22, 24, 19, 26, 27, 23, 28, 30, 25, 32, 33, 31, 34, 36, 35, 38, 39, 40, 29, 42, 43, 44, 45, 46, 48, 37, 50, 51, 52, 41, 54, 55, 56, 49, 58, 57, 60, 47, 62, 63, 64, 53, 66, 65, 68, 59, 70 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS As prime(1)=2, this sequence can always be extended with an even number. This sequence is a permutation of the natural numbers, with inverse A285041 (say prime(k) divides n: the sequence contains all the multiples of 2*k, hence n will eventually be chosen). This sequence has a fractal structure that is highlighted in the illustrations of some derived sequences in the Links section. LINKS Rémy Sigrist, Table of n, a(n) for n = 1..10000 Rémy Sigrist, Scatterplot of a(n)-n Rémy Sigrist, Scatterplot of Sum_{k=1..n} (-1)^a(n) Rémy Sigrist, PARI program for A285039 CROSSREFS Cf. A285041 (inverse). Sequence in context: A123718 A121878 A167905 * A260307 A285041 A265734 Adjacent sequences:  A285036 A285037 A285038 * A285040 A285041 A285042 KEYWORD nonn AUTHOR Rémy Sigrist, Apr 08 2017 STATUS approved

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Last modified December 5 16:12 EST 2019. Contains 329753 sequences. (Running on oeis4.)