Define a sequence of string of 0’s and 1’s: 1 The first string,
s0, is just the empty string "". The second string, s1, is 1. The
third, fourth, fifth, . . . strings are defined as follows: si =
si−11ti−1 where ti−1 is the reverse of si−1 with all 0s replaced by
1s and all 1s replaced by 0s. The first few strings are s0 = "", s1
= 1, s2 = 110, s3 = 1101100, s4 = 110110011100100....