A049705 a(n)=3-k(n), where k=A000002=Kolakoski sequence; also the sequence of runlengths of a is k.

2, 1, 1, 2, 2, 1, 2, 1, 1, 2, 1, 1, 2, 2, 1, 2, 2, 1, 1, 2, 1, 2, 2, 1, 2, 1, 1, 2, 2, 1, 2, 2, 1, 2, 1, 1, 2, 1, 1, 2, 2, 1, 2, 1, 1, 2, 1, 2, 2, 1, 2, 2, 1, 1, 2, 1, 1, 2, 2, 1, 2, 1, 1, 2, 1, 1, 2, 2, 1, 2, 2, 1, 2, 1, 1, 2, 1, 2, 2, 1, 1, 2, 1, 1, 2, 2, 1, 2, 1, 1, 2, 1, 1, 2, 2, 1, 2, 2, 1, 1, 2, 1, 2, 2, 1

Offset

1,1

Comments

The anti-Kolakoski sequence: a(n) never equals the length of the n-th run. Start with a(1)=2, then the first run is of length 1 and a(2)=1; thus the 2nd run is of length 2 and a(3)=1, thus a(4)=a(5)=2, etc. - Jean-Christophe Hervé, Nov 10 2014

Links

Table of n, a(n) for n=1..105.

Mathematica

a2 = {1, 2, 2}; Do[ a2 = Join[a2, {1 + Mod[n-1, 2]}], {n, 3, 70}, {i, 1, a2[[n]]}]; 3 - a2 (* Jean-François Alcover, Jun 18 2013 *)

Crossrefs

Cf. A088569 (essentially the same sequence).

Sequence in context: A264714 A265209 A202340 * A060236 A006345 A122497

Adjacent sequences: A049702 A049703 A049704 * A049706 A049707 A049708

Keyword

nonn

Author

Clark Kimberling

Status

approved