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 A057115 Order-preserving permutation of the rational numbers (x -> x-1); positions in Stern-Brocot tree. 9
 2, 4, 1, 8, 9, 5, 3, 16, 17, 18, 19, 10, 11, 6, 7, 32, 33, 34, 35, 36, 37, 38, 39, 20, 21, 22, 23, 12, 13, 14, 15, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 40, 41, 42, 43, 44, 45, 46, 47, 24, 25, 26, 27, 28, 29, 30, 31, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS FORMULA a(n) = frac2position_in_whole_SB_tree(sbtree_perm_1_1_left(SternBrocotTreeNum(n)/SternBrocotTreeDen(n))) MAPLE sbtree_perm_1_1_left := x -> (`if`((x <= 0), x, (`if`((x < 1), (x/(1+x)), (`if`((x < 2), (1/(3-x)), (x-1))))))); CROSSREFS Inverse permutation: A057114. When conjugated with A059893, one gets A065260, a valid siteswap permutation. The first row of A065626, i.e. a(n) = RotateNodeLeft(1, n). Sequence in context: A254179 A328641 A208741 * A065276 A065288 A065264 Adjacent sequences:  A057112 A057113 A057114 * A057116 A057117 A057118 KEYWORD nonn AUTHOR Antti Karttunen, Aug 09 2000 STATUS approved

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Last modified June 2 14:18 EDT 2020. Contains 334782 sequences. (Running on oeis4.)