login
This site is supported by donations to The OEIS Foundation.

 

Logo

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A064664 Regard A064413 as giving a permutation of the positive integers; sequence gives inverse permutation. 21
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

T. D. Noe and 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.

Eric Weisstein's World of Mathematics, EKG Sequence

Index entries for sequences related to EKG sequence

Index entries for sequences that are permutations of the natural numbers

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

Cf. A064413, A064665-A064669. Equals A064421 + 1.

Sequence in context: A163233 A096666 A191855 * A078386 A163254 A277696

Adjacent sequences:  A064661 A064662 A064663 * A064665 A064666 A064667

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Oct 11 2001

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 18 05:30 EST 2019. Contains 319269 sequences. (Running on oeis4.)