Generating 8 MHz clock using Arduino Micro

Projects Programming
5 
fOCnA = fclk_I/O / ( 2 * N * (1 + OCRnA) )
fclk_I/O = 16 MHz
N = 1
OCRnA = 3
fOCnA = 16000000 / ( 2 * 1 * (1 + 3) )
fOCnA = 2000000 = 2 MHz

So, there are two problems. The first is that you are using the wrong value for OCRnA. The second is that the output frequency is 125 Hz instead of 2 MHz.