A264119 - OEIS

%I #30 Apr 03 2016 10:45:16

%S 1,1,1,2,2,1,1,2,1,1,1,2,2,1,1,2,2,1,1,2,1,1,1,2,2,1,1,2,1,1,1,2,2,1,

%T 1,2,2,1,1,2,1,1,1,2,2,1,1,2,2,1,1,2,1,1,1,2,2,1,1,2,1,1,1,2,2,1,1,2,

%U 2,1,1,2,1,1,1,2,2,1,1,2,1,1,1,2,2,1,1,2,2,1,1,2,1,1,1,2,2,1,1,2,2,1,1,2,1

%N Look and say for Fibonacci word A003842.

%C Define strings S(0)=2, S(1)=1, S(n)=S(n-1)S(n-2); iterate.

%C A003842 is S(infinity) and begins 1, 2, 1, 1, 2, 1, 2.

%C We see one 1, one 2, two 1, one 2, one 1, one 2.

%C So this sequences begins 1,1, 1,2, 2,1, 1,2, 1,1, 1,2.

%H Patrice Séébold, <a href="http://www.numdam.org/item?id=ITA_2008__42_4_729_0">Look and Say Fibonacci</a>, RAIRO-Theor. Inf. Appl. 42 (2008) 729-746.

%o (PARI) lns(v) = {vls = []; nb = 0; old = -1; for (k=1, #v, if (v[k] == old, nb++, if (old != -1, vls = concat(vls, nb); vls = concat(vls, old);); nb = 1;); old = v[k];); vls = concat(vls, nb); vls = concat(vls, old); vls;}

%o lista(nn=11) = {v = [2]; w = [1]; for (k=1, nn, nw = concat(w, v); v = w; w = nw;); lns(w);}

%Y Cf. A003842.

%K nonn

%O 0,4

%A _Michel Marcus_, Apr 03 2016