Metamath Proof Explorer

Theorem mucl

Description: Closure of the Möbius function. (Contributed by Mario Carneiro, 22-Sep-2014)

Ref Expression
Assertion mucl 
|- ( A e. NN -> ( mmu ` A ) e. ZZ )

Proof

Step Hyp Ref Expression
1 muf 
 |-  mmu : NN --> ZZ
2 1 ffvelrni 
 |-  ( A e. NN -> ( mmu ` A ) e. ZZ )