An array , of positive integers is called an interspersion if
1. The rows of comprise a partition of the positive integers,
2. Every row of is an increasing sequence,
3. Every column of is a (possibly finite) increasing sequence,
4. If and are distinct rows of and if and are any indices for which , then .
If an array is an interspersion, then it is a sequence dispersion. If an array is an interspersion, then the sequence given by for some is a fractal sequence. Examples of interspersion are the Stolarsky array and Wythoff array.