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A074276 Positions of occurrences of 2,1,1,2,1 in the Kolakoski sequence A000002. 3
3, 12, 21, 27, 30, 39, 47, 57, 66, 69, 84, 93, 102, 111, 114, 120, 129, 139, 156, 166, 174, 183, 189, 192, 207, 216, 219, 225, 237, 243, 252, 264, 270, 273, 282, 290, 309, 318, 327, 336, 351, 354, 363, 380, 386, 398, 407, 416, 425, 437, 443, 462, 471, 480 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Nathaniel Johnston, Table of n, a(n) for n = 1..10000

EXAMPLE

The Kolakoski sequence begins 1,2,2,1,1,2,1,2,2,1,2,2,1,1,2,1,..., so 2,1,1,2,1 occurs at positions 3 and 12.

MATHEMATICA

a2 = {1, 2, 2}; Do[a2 = Join[a2, {1 + Mod[n - 1, 2]}], {n, 3, 400}, {i, 1, a2[[n]]}]; a2 //. {a___, 2, 1, 1, 2, 1, b___} :> {a, 0, 1, 1, 2, 1, b} // Flatten // Position[#, 0] & // Flatten (* Jean-Fran├žois Alcover, Jun 18 2013 *)

CROSSREFS

Cf. A074275, A074277.

Sequence in context: A256131 A080767 A043465 * A055041 A061819 A017197

Adjacent sequences:  A074273 A074274 A074275 * A074277 A074278 A074279

KEYWORD

nonn,easy

AUTHOR

Jon Perry, Sep 21 2002

EXTENSIONS

Extended and offset corrected by Nathaniel Johnston, May 02 2011

STATUS

approved

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Last modified November 18 22:50 EST 2019. Contains 329305 sequences. (Running on oeis4.)