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A064664
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Regard A064413 as giving a permutation of the positive integers; sequence gives inverse permutation.
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30
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1, 2, 5, 3, 10, 4, 14, 8, 6, 9, 20, 7, 28, 13, 11, 17, 33, 12, 37, 18, 15, 19, 43, 16, 24, 27, 22, 26, 57, 23, 61, 31, 21, 32, 25, 30, 67, 36, 29, 40, 74, 35, 81, 41, 39, 42, 89, 45, 50, 46, 34, 47, 100, 48, 53, 49, 38, 56, 107, 52, 115, 60, 51, 64, 54, 59, 128, 65, 44, 55
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OFFSET
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1,2
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COMMENTS
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The Mathematica program computes the EKG sequence A064413 and then determines the inverse permutation. - T. D. Noe, Nov 13 2002
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LINKS
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J. C. Lagarias, E. M. Rains, and N. J. A. Sloane, The EKG sequence, Exper. Math. 11 (2002), 437-446; arXiv preprint, arXiv:math/0204011 [math.NT], 2002.
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EXAMPLE
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Original permutation has cycles (1) (2) (3, 4, 6, 9, 10, 5) (..., 20, 18, 12, 7, 14, 13, 28, 26, ...) (8) ...
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MATHEMATICA
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maxN=200; lst={1, 2}; unused=Range[3, maxN]; found=True; While[found, found=False; i=0; While[ !found&&i<Length[unused], i++; If[GCD[lst[[ -1]], unused[[i]]]>1, found=True; AppendTo[lst, unused[[i]]]; unused=Delete[unused, i]]]]; Take[Ordering[lst], unused[[1]]-1]
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PROG
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(Haskell)
import Data.List (elemIndex); import Data.Maybe (fromJust)
a064664 = (+ 1) . fromJust . (`elemIndex` a064413_list)
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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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