FindRepeat

FindRepeat[list] finds the minimal sublist or subarray that repeats to give list.

FindRepeat[list,n] requires that the sublist be repeated at least n times in list.

FindRepeat[list,{n1,n2,…}] requires ni to repeat at level i in list.

FindRepeat["string"] finds the minimal substring that repeats to give string.

FindRepeat["string",n] requires that the substring be repeated at least n times.

Please visit the official Wolfram Language Reference for more details and examples on core symbols.