func μ(n) {
    var f = n.factor_exp.map { .tail }
    f.any { _ > 1 } ? 0 : ((-1)**f.sum)
}

with (199) { |n|
    say "Values of the Möbius function for numbers in the range 1..#{n}:"
    [' '] + (1..n->map(μ)) -> each_slice(20, {|*line|
        say line.map { '%2s' % _ }.join(' ')
    })
}