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A071907 Kolakoski-(1,4) sequence: a(n) is length of n-th run. 7
1, 4, 4, 4, 4, 1, 1, 1, 1, 4, 4, 4, 4, 1, 1, 1, 1, 4, 1, 4, 1, 4, 4, 4, 4, 1, 1, 1, 1, 4, 4, 4, 4, 1, 1, 1, 1, 4, 1, 4, 1, 4, 4, 4, 4, 1, 4, 4, 4, 4, 1, 4, 4, 4, 4, 1, 1, 1, 1, 4, 4, 4, 4, 1, 1, 1, 1, 4, 1, 4, 1, 4, 4, 4, 4, 1, 1, 1, 1, 4, 4, 4, 4, 1, 1, 1, 1, 4, 1, 4, 1, 4, 4, 4, 4, 1, 4, 4, 4, 4, 1, 4, 4, 4, 4 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

1444411, 14444111144441111414144441111 are primes. - Vincenzo Librandi, Mar 02 2016

LINKS

Ivan Neretin, Table of n, a(n) for n = 1..10000

Michael Baake and Bernd Sing, Kolakoski-(3,1) is a (deformed) model set, arXiv:math/0206098 [math.MG], 2002-2003.

Rémy Sigrist, Scatterplot of twice the number of ones among the first n terms of the sequence minus n for n = 1..1000000

MATHEMATICA

seed = {1, 4}; w = {}; i = 1; Do[w = Join[w, Array[seed[[Mod[i - 1, Length[seed]] + 1]] &, If[i > Length[w], seed, w][[i]]]]; i++, {n, 42}]; w (* Ivan Neretin, Apr 02 2015 *)

CROSSREFS

Cf. A000002, A071820, A064353, A071928, A071942.

Sequence in context: A274947 A279406 A171408 * A172369 A190338 A199177

Adjacent sequences:  A071904 A071905 A071906 * A071908 A071909 A071910

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified September 19 04:39 EDT 2019. Contains 327187 sequences. (Running on oeis4.)