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1, 2, 3, 5, 13, 11, 28, 4, 6, 18, 17, 25, 8, 39, 14, 46, 23, 7, 26, 33, 9, 20, 43, 29, 58, 10, 12, 48, 35, 63, 32, 73, 41, 15, 38, 102, 47, 60, 16, 53, 171, 44, 61, 56, 72, 19, 50, 93, 59, 78, 62, 88, 21, 67, 103, 74, 108
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,2
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COMMENTS
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Conjectured to be a permutation of the natural numbers.
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REFERENCES
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L. Edson Jeffery, Posting to Sequence Fans Mailing List, Dec 01 2014
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LINKS
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David L. Applegate, Hans Havermann, Bob Selcoe, Vladimir Shevelev, N. J. A. Sloane, and Reinhard Zumkeller, The Yellowstone Permutation, arXiv preprint arXiv:1501.01669, 2015.
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MATHEMATICA
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max = 57; f = True; a = {1, 3, 5}; NN = Range[4, 1000]; s = 2*NN - 1; While[TrueQ[f], For[k = 1, k <= Length[s], k++, If[Length[a] < max, If[GCD[a[[-1]], s[[k]]] == 1 && GCD[a[[-2]], s[[k]]] > 1, a = Append[a, s[[k]]]; s = Delete[s, k]; k = 0; Break], f = False]]]; Table[(a[[n]] + 1)/2, {n, max}] (* L. Edson Jeffery, Dec 02 2014 *)
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PROG
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(Python)
from __future__ import division
from fractions import gcd
A251414_list, l1, l2, s, b = [1, 2, 3], 5, 3, 7, {}
for _ in range(1, 10**2):
....i = s
....while True:
........if not i in b and gcd(i, l1) == 1 and gcd(i, l2) > 1:
............A251414_list.append((i+1)//2)
............l2, l1, b[i] = l1, i, True
............while s in b:
................b.pop(s)
................s += 2
............break
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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