A substring of a string is a subsequence of contiguous symbols in the string. For example, 00 is a substring of 001 but not of 010. For this sequence we do not count the multiplicity of occurrence of common substrings.
a(7) = 4 since the two strings 0001011 and 0011010 have as maximum length common substrings the 4 strings 011,001,101,010 and computer search shows that no other pair of strings of length 7 has more than 4 common maximum length substrings.
