%I #3 Mar 30 2012 18:37:43
%S 1,2,5,15,49,169,604,2212,8244,31128,118716,456337,1765251
%N Length of lists created by n substitutions k -> Range[ -Floor[Abs[k]/2],Floor[Abs[k]+3/2]] starting with {0}.
%e {0}, {0,1}, {0,1,0,1,2}, {0,1,0,1,2,0,1,0,1,2,-1,0,1,2,3}
%t {Length/@Flatten/@NestList[ # /. k:(_Integer|_Rational):>Range[ -Floor[Abs[k]/2], Floor[Abs[k]+3/2]]&, {0}, 11]}
%K nonn
%O 0,2
%A _Wouter Meeussen_, May 11 2003