quadratic representation

The number of representations of n by k squares, allowing zeros and distinguishing signs and order, is denoted r_k(n). The special case k = 2 corresponding to two squares is often denoted simply r_2(n) = r(n) (e.g., Hardy and Wright 1979, p. 241; Shanks 1993, p. 162).

class number | Diophantine equation--2nd powers | Fermat's polygonal number theorem | Gauss's circle problem | Landau-Ramanujan constant | Leibniz series | prime factor | primitive Pythagorean triple | Pythagorean quadruple | Pythagorean triple | Sierpiński constant | tau function