Lifting The Exponent Lemma for Sums
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Theorem
Let $x, y \in \Z$ be integers with $x + y \ne 0$.
Let $n \ge 1$ be an odd natural number.
Let $p$ be an odd prime.
Let:
- $p \divides x + y$
and:
- $p \nmid x y$
where $\divides$ and $\nmid$ denote divisibility and non-divisibility respectively.
Then:
- $\map {\nu_p} {x^n + y^n} = \map {\nu_p} {x + y} + \map {\nu_p} n$
where $\nu_p$ denotes $p$-adic valuation.
Proof
This follows from the Lifting The Exponent Lemma with $y$ replaced by $-y$.
$\blacksquare$