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A054085
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a(n) = order of in the permutation A054084 of the natural numbers if this order exists; a(n) = -1 otherwise.
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2
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2, 2, 7, 7, 7, 7, 7, 7, 9, 7, 9, 9, 9, 9, 9, 9, -1, 9, -1, 9, -1, -1, -1, -1, 16, -1, 16, -1, 16, -1, -1, 16, 16, 16, 16, 16, -1, -1, 16, 16, -1, 16, -1, 16, -1, -1, 16, -1, -1, 16, -1, 16, -1, -1, -1, -1, -1, -1, -1, -1, -1, 16, -1, -1, -1, -1, -1, -1, -1
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OFFSET
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1,1
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LINKS
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EXAMPLE
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3 -> 5 -> 7 -> 10 -> 8 -> 6 -> 4 -> 3, so that 3 has order 7.
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MATHEMATICA
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a054084[n_] := a054084[n] = If[EvenQ[n], Floor[n/2*GoldenRatio],
Floor[(n + 1)/2*GoldenRatio^2]];
Array[a054084[#] &, 40] (* after Jean-François Alcover *)
Table[Length[NestWhileList[a054084, a054084[n], # != n &, 1,
10000]] /. (10001 -> -1), {n, 1, 500}]
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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