Hilbert-Waring Theorem/Particular Cases/4

Particular Case of the Hilbert-Waring Theorem: $k = 4$
The Hilbert-Waring Theorem states that:

The case where $k = 4$ is:

Every positive integer can be expressed as the sum of at most $19$ powers of $4$.

That is:
 * $g \left({4}\right) = 19$