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%I #5 Mar 30 2012 18:39:24
%S 1,2,11,21,221,22112,11221211,21221121121,2212211212212112,
%T 1122122112122122112112122,12112212211212212211211221211212212211,
%U 211212211211221211211221221121221211221221211211221221121
%N Successive generations of an alternating Kolakoski rule.
%C Strings are obtained using the Kolakoski substitution and the additional rule : start with 1 if previous string ends with 2, start with 2 if previous string ends with 1. The concatenation of those strings gives 1211212212211211221211...which is A006928 word. If you replace the initial 1 with 12 you get 122112122122112112212...the infinite Kolakoski word A000002.
%F Conjecture : length of n-th string is asymptotic to c*(3/2)^n for some c.
%e 1-->2-->11-->21-->221-->22112-->11221211
%Y Cf. A000002, A054349.
%K nonn,base
%O 1,2
%A _Benoit Cloitre_, Oct 11 2005
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