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A064421 Term at which n appears in A064413 (if it begins at 2). 13
0, 1, 4, 2, 9, 3, 13, 7, 5, 8, 19, 6, 27, 12, 10, 16, 32, 11, 36, 17, 14, 18, 42, 15, 23, 26, 21, 25, 56, 22, 60, 30, 20, 31, 24, 29, 66, 35, 28, 39, 73, 34, 80, 40, 38, 41, 88, 44, 49, 45, 33, 46, 99, 47, 52, 48, 37, 55, 106, 51, 114, 59, 50, 63, 53, 58, 127, 64, 43, 54, 133 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Every nonnegative number appears here exactly once.

LINKS

Table of n, a(n) for n=1..71.

J. C. Lagarias, E. M. Rains and N. J. A. Sloane, The EKG sequence, Exper. Math. 11 (2002), 437-446.

Index entries for sequences related to EKG sequence

MATHEMATICA

terms = 100;

ekg[s_] := Block[{m = s[[-1]], k = 3}, While[MemberQ[s, k] || GCD[m, k] == 1, k++]; Append[s, k]];

EKG = Nest[ekg, {2, 4}, 2 terms];

a[1] = 0; a[n_] := FirstPosition[EKG, n] // First;

Array[a, terms] (* Jean-Fran├žois Alcover, Aug 30 2018, after Robert G. Wilson v *)

CROSSREFS

Cf. A064413. Equals A064664 - 1.

Sequence in context: A060734 A075594 A076022 * A051494 A262025 A118013

Adjacent sequences:  A064418 A064419 A064420 * A064422 A064423 A064424

KEYWORD

nonn

AUTHOR

Jonathan Ayres (Jonathan.ayres(AT)btinternet.com), Sep 30 2001

EXTENSIONS

More terms from Naohiro Nomoto, Sep 30 2001

STATUS

approved

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Last modified November 17 21:07 EST 2018. Contains 317278 sequences. (Running on oeis4.)