Definition:Prime-Counting Function/Also defined as

Prime-Counting Function: Also defined as

Some sources give both the domain and codomain of the prime-counting function as $\N$, thus:

$\pi: \N \to \N$

Sources

• 2008: David Joyner: Adventures in Group Theory (2nd ed.) ... (previous) ... (next): Chapter $2$: 'And you do addition?': $\S 2.1$: Functions: Example $2.1.1$