OFFSET
1,4
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
FORMULA
a(p)=0 for any prime p, because there is only one group of prime order.
EXAMPLE
For n=4, a(4)=2 because if Cayley table cells are T[0][0]=0, T[1][1]=2 the group is Z4 (not Z2*Z2).
For n=12, a(12)=3 because if Cayley table cells are T[0][0]=1, T[1][1]=2, T[0][2]=3, the group is Z12 (the order of T[0][0] neither 3 no 4).
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Andrey Chernev, Oct 08 2025
EXTENSIONS
a(16)-a(23) from Andrey Chernev, Feb 18 2026
STATUS
approved
