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A064664 Regard A064413 as giving a permutation of the positive integers; sequence gives inverse permutation. 30
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
The Mathematica program computes the EKG sequence A064413 and then determines the inverse permutation. - T. D. Noe, Nov 13 2002
LINKS
Ray Chandler, Table of n, a(n) for n = 1..10000 (first 1000 terms from T. D. Noe)
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.
Eric Weisstein's World of Mathematics, EKG Sequence.
EXAMPLE
Original permutation has cycles (1) (2) (3, 4, 6, 9, 10, 5) (..., 20, 18, 12, 7, 14, 13, 28, 26, ...) (8) ...
MATHEMATICA
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]
PROG
(Haskell)
import Data.List (elemIndex); import Data.Maybe (fromJust)
a064664 = (+ 1) . fromJust . (`elemIndex` a064413_list)
-- Reinhard Zumkeller, May 01 2014, Sep 17 2011
CROSSREFS
Equals A064421 + 1.
Sequence in context: A163233 A096666 A191855 * A352188 A323637 A349637
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Oct 11 2001
STATUS
approved

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Last modified June 26 05:11 EDT 2024. Contains 373715 sequences. (Running on oeis4.)