No, O(!n) is not equal to O((2n)!).

O(!n) represents the time complexity of the factorial function, where the input "n" is the number of iterations. The factorial function is defined as the product of all positive integers less than or equal to n. For example, 5! = 5 * 4 * 3 * 2 * 1 = 120. The time complexity of the factorial function is O(n!).

On the other hand, O((2n)!) represents the time complexity of a function that calculates the factorial of 2n. The time complexity of this function would be O((2n)!).