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.