OFFSET
1,2
LINKS
Andrey Chernev and Nikolay Chernev, On the smallest Cayley table fill that uniquely determines a semigroup (in Russian).
Nikolay Chernev, Cayley_tables_unique GitHub repository.
EXAMPLE
For n=1, a(1)=0 because there is only one semigroup of order 1.
For n=2 and 3, a(2)=a(3)=2 because if Cayley table cells are T[0][0]=1, T[1][1]=0 then semigroup is determined uniquely (see the program in the repository).
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Andrey Chernev, Oct 08 2025
EXTENSIONS
a(6) corrected and a(7) from Andrey Chernev, Feb 18 2026
STATUS
approved
