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A074275
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Positions of occurrences of 1,2,2,1,2 in the Kolakoski sequence A000002.
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3
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7, 17, 34, 43, 52, 61, 73, 79, 88, 98, 106, 125, 134, 143, 149, 152, 161, 170, 179, 196, 202, 211, 230, 233, 248, 257, 260, 277, 286, 295, 298, 304, 313, 323, 331, 340, 346, 358, 367, 373, 376, 391, 394, 403, 411, 421, 430, 433, 448, 451, 457, 466, 476, 493
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OFFSET
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1,1
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LINKS
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EXAMPLE
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The Kolakoski sequence begins 1,2,2,1,1,2,1,2,2,1,2,2,1,1,2,1,1,1,2,2,1,2,..., so 1,2,2,1,2 occurs at positions 7 and 17.
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MATHEMATICA
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a2 = {1, 2, 2}; Do[ a2 = Join[a2, {1 + Mod[n - 1, 2]}], {n, 3, 400}, {i, 1, a2[[n]]}]; a2 //. {a___, 1, 2, 2, 1, 2, b___} :> {a, 0, 2, 2, 1, 2, b} // Flatten // Position[#, 0] & // Flatten (* Jean-François Alcover, Jun 18 2013 *)
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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