%I #3 Mar 31 2012 13:21:18
%S 5,7,7,8,8,14,19,24,28,31,36,42,45,47,49,50,50,50,51,51,51,54,55,55,
%T 55,56,56,56,58,60,61,61,61,62,62,62,65,66,66,66,67,67,67,70,72,74,75,
%U 75,75,76,76,76,79,80,80,80,81,81,81,83,85,86,86,86,87,87,87,92,93,93
%N Number of opening (equally: closing) brackets in each term of Wolfram's Symbolic Rewriting system A154473-A154474.
%C 2*a(n) gives the number of bits in A154474(n).
%H A. Karttunen, <a href="/A154475/b154475.txt">Table of n, a(n) for n = 0..100</a>
%H S. Wolfram, <a href="http://www.wolframscience.com/nksonline/page-102">A New Kind of Science, Wolfram Media Inc., (2002), p. 102</a>, <a href="http://www.wolframscience.com/nksonline/page-103">p. 103</a> and pages 104, 896-898.
%F a(n) = A072643(A154472(n)).
%e The iteration starts from the initial term e[e[e][e]][e][e], which contains 5 ['s (and also 5 ]'s), thus a(0)=5.
%Y a(n) = A029837(1+A154473(n))/2. a(n) = A154476(n)-1.
%K nonn
%O 0,1
%A _Antti Karttunen_, Jan 11 2009