rw [h, multiplicity.Finset.prod Int.prime_two, Nat.cast_sum]
k n : ℕ
hk : k > 0
h : ↑k ! = ∏ i ∈ Finset.range n, (2 ^ n - 2 ^ i)
⊢ multiplicity 2 ↑k ! = ↑(∑ i ∈ Finset.range n, i)
k n : ℕ
hk : k > 0
h : ↑k ! = ∏ i ∈ Finset.range n, (2 ^ n - 2 ^ i)
⊢ ∑ x ∈ Finset.range n, multiplicity 2 (2 ^ n - 2 ^ x) = ∑ x ∈ Finset.range n, ↑x