Yang Hui's triangle
Perhaps the most well-known two-dimensional number pattern is the triangular array of binomial coefficients most commonly referred to as Pascal's triangle. However, the pattern had been known and studied well before Blaise Pascal (1623-1662). In centuries before Pascal, mathematicians in India, Greece, Iran, China, Germany and Italy had studied it - although it is fair to say that Pascal conducted the most thorough and organized study of this fascinating array of numbers.