A special subset of spectrum sequences, which use an irrational number as the spectrum base. Using the base k, the sequence is therefore:
[k], [2k], [3k], ...
where [ ] is the floor function.
A special property of any Beatty sequence is that, if we pick two bases a and b such that
1 1
--- + --- = 1
a b
Then the Beatty sequences with a and b as bases contain between them all the natural numbers, without duplication! I'm unsure of the proof for this, but I shall look into it.