A264119 Look and say for Fibonacci word A003842.

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, 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, 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

Offset: 0

Author

Michel Marcus, Apr 03 2016

Keywords

• nonn

Comments

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

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

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

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

Links

• Patrice Séébold, Look and Say Fibonacci, RAIRO-Theor. Inf. Appl. 42 (2008) 729-746.

Crossrefs

Cf. A003842.

Programs

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