Any process (usually in the form of an algebraic formula) which is defined by a starting value (or values) and a formula for calculating the next value.
The 'output' of applying this formula then becomes the 'input' for the next application of the same formula, and so on .....
| x0 = 1, | xr+1 = xr + 2 | (produces the odd numbers) | |
| x0 = 1, | x1 = 1, | xr+2 = xr+1 + xr | (produces the Fibonacci Series) |
| z0 = 0 + 0i, | zr+1 = zr2 + c | (the Mandelbrot formula) |