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Math and science::Algebra::Aluffi
Euler's \( \phi \)
Euler's \( \phi \)-function
Euler's \( \phi \)-function maps any positive integer \( m \) to the number of [what?]. In other words:
[
\[ \phi(m) = \left| \; \{ r \in \mathbb{N} : \quad ? \quad\} \; \right| \] ]
A related theorem:
Theorem. N = sum of relative primes of divisors of N.
\[ \sum_{m > 0, m | n} \phi(m) = n\]
Proof is on the reverse side.
