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 A257862 a(n) = n if n <= 3, otherwise a(n) is the smallest number not already used and relatively prime to a(n-1) such that the set of prime divisors of one of the numbers {a(n-2), a(n)} is a subset of the set of prime divisors of the other. 1
 1, 2, 3, 4, 9, 8, 15, 14, 5, 7, 10, 21, 16, 27, 20, 33, 25, 11, 30, 77, 6, 49, 12, 35, 18, 125, 24, 55, 32, 121, 26, 99, 13, 66, 65, 22, 169, 44, 39, 64, 81, 28, 45, 56, 75, 98, 135, 112, 165, 128, 225, 34, 105, 17, 63, 68, 147, 136, 189, 170, 231, 40, 243, 50 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS The sequence is an analog of the Yellowstone sequence A098550 with a more stringent condition on neighboriong terms at distance 2. However, we conjecture that, as with A098550, this is a permutation of the positive integers. By definition, every pair of neighboring terms at distance 2 are strictly connected numbers as defined in comment in A257112. LINKS Peter J. C. Moses, Table of n, a(n) for n = 1..2000 CROSSREFS Cf. A098550, A257112, A255348. Sequence in context: A098550 A256224 A255509 * A329449 A227928 A098293 Adjacent sequences:  A257859 A257860 A257861 * A257863 A257864 A257865 KEYWORD nonn AUTHOR Vladimir Shevelev, May 11 2015 EXTENSIONS More terms from Peter J. C. Moses, May 11 2015 STATUS approved

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Last modified September 27 00:14 EDT 2020. Contains 337378 sequences. (Running on oeis4.)