A074275 Positions of occurrences of 1,2,2,1,2 in the Kolakoski sequence A000002.

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

Offset

1,1

Links

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

Example

The Kolakoski sequence begins 1,2,2,1,1,2,1,2,2,1,2,2,1,1,2,1,1,1,2,2,1,2,..., so 1,2,2,1,2 occurs at positions 7 and 17.

Mathematica

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 *)

Crossrefs

Cf. A074276, A074277.

Sequence in context: A301695 A301725 A278920 * A051411 A195016 A296553

Adjacent sequences: A074272 A074273 A074274 * A074276 A074277 A074278

Keyword

nonn,easy

Author

Jon Perry, Sep 21 2002

Extensions

Extended and offset corrected by Nathaniel Johnston, May 02 2011

Status

approved