As later computer graphics made quite clear, although some kind of diagonal structures may simply arise from diagonals alternatively containing odd and even number, it is intriguing that the prime number tend to lie on some diagonal lines more than the discovery of patterns, Ulam’s simple demonstration highlights the use of the computer as a kind of microscope that allows mathematicians to visualize structures that may lead to new theorems. This kind of investigation in the early 1960s gradually gave rise to the explosion in experimental mathematics toward the end of the twentieth century.