Unary coding

Unary coding is an entropy encoding that represents a Natural number n with n-1 ones followed by a zero. For example 5 is represented as 11110.

Unary coding is an optimally efficient encoding for the following discrete probability distribution:

${\displaystyle P(n)=2^{-n}}$

For n=1,2,3,...

A modified unary encoding is used in UTF-8.