You changed the required signature of the function. It should return, quotint the description, "top rows of Pascal's Triangle flattened into a one-dimensional list/array", and you changed it to int[,].

Usually problems are related to overflow, and you can verify this by comparing your results to, for example, results returned by Wolfram: https://www.wolframalpha.com/input/?i=binomial%2860%2C30%29 .
Run your solution locally for n=60, dump the answer to the console, and check numbers in the middle of the row, because these are the largest: (59 28), (60 30) etc.

It's possible that your calculations either overflow, or are inaccurate due to floating point division.

I have almost the same "Expected" and "but was" in the error for random and 60th, but it's quite hard to check all numbers. Anyway, any number i check is correct aaccording to "expected". What can be the problem?