%I #21 Mar 06 2015 23:32:38
%S 1,1,0,1,0,1,1,0,1,1,1,0,0,1,1,0,0,1,1,1,0,0,0,1,0,0,1,1,0,1,1,0,1,1,
%T 0,0,0,1,1,0,0,1,1,0,0,1,1,0,1,1,1,1,0,0,0,1,0,0,0,1,1,0,0,1,0,1,1,0,
%U 1,1,1,0,0,1,0,0,1,1,1,0,0,1,1,0,1
%N "Look and say" sequence, but say everything mod 2; starting with 1101.
%C Similar to A248392, only now the initial number is 1101 rather than 1. See A248392 for more details. A248392 and this sequence are the two most interesting fractal structures they discovered.
%D Alex Kontorovich, Verbal communication to N. J. A. Sloane, Oct 16 2014, describing work that he and Sam Payne did around 1998.
%H Alex Kontorovich, <a href="http://math.rutgers.edu/~alexk/progs.html">Programs</a>
%H Alex Kontorovich, <a href="/A248396/a248396.jpg">Illustration of initial terms</a>
%e The initial "numbers" are:
%e 1101
%e 011011
%e 10011001
%e 1100010011
%e 0110110001
%e 100110011011
%e 11000100011001
%e 01101110010011
%e 1001101100110001
%e 110001100100011011
%e 011001001110011001
%e 10010011001100010011
%e 1100110001000110110001
%e 0100011011100110011011
%e 101110011011000100011001
%e 11101100011001101110010011
%e 11100110010001101100110001
%e 11000100111001100100011011
%e 01101100110001001110011001
%e 1001100100011011001100010011
%e 110001001110011001000110110001
%e ...
%e The illustration gives a longer list and shows the fractal-like structure more clearly.
%p # a[n] is the n-th "number" read from right to left.
%p a[1]:=[1,0,1,1]:
%p M:=32:
%p for n from 1 to M do
%p s:=a[n-1][1]; a[n]:=[]; r:=1;
%p for i from 2 to nops(a[n-1]) do
%p t:=a[n-1][i];
%p if s=t then r:=r+1;
%p else a[n]:=[op(a[n]), s, r mod 2]; s:=t; r:=1;
%p fi;
%p od:
%p a[n]:=[op(a[n]), s, r mod 2];
%p od:
%p for n from 1 to M do m:=nops(a[n]); lprint([seq(a[n][m-i+1],i=1..m)]); od:
%Y Cf. A248932, A005150.
%K nonn,base
%O 1
%A _N. J. A. Sloane_, Oct 18 2014