The number of binary bits necessary to represent a number, given explicitly by
(1)
| |||
(2)
|
where is the ceiling function, is the floor function, and is lg, the logarithm to base 2. For , 1, 2, ..., the sequence of bit lengths is given by 0, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, ... (OEIS A029837). The function is given by the Wolfram Language function BitLength[n].