mobius ( n -- x )

Vocabulary

math.extras

Inputs

n

an object

Outputs

x

an object

Definition

USING: assocs kernel math math.primes.factors sequences ;

IN: math.extras

: mobius ( n -- x )
    group-factors values
    [ 1 ]
    [ dup [ 1 > ] any? [ drop 0 ] [ length even? 1 -1 ? ] if ]
    if-empty ;