Möbius function

Möbius number is not defined for n == 0. Raku arrays are indexed from 0 so store a blank value at position zero to keep n and μ(n) aligned.

use Prime::Factor;

sub μ (Int \n) {
    return 0 if n %% (4|9|25|49|121);
    my @p = prime-factors(n);
    +@p == [e-mail] ?? +@p %% 2 ?? 1 !! -1 !! 0
}

my @möbius = lazy flat '', 1, (2..*).hyper.map: &μ;

# The Task
put "Möbius sequence - First 199 terms:\n",
    @möbius[^200]».fmt('%3s').batch(20).join: "\n";

Output:

Möbius sequence - First 199 terms:
      1  -1  -1   0  -1   1  -1   0   0   1  -1   0  -1   1   1   0  -1   0  -1
  0   1   1  -1   0   0   1   0   0  -1  -1  -1   0   1   1   1   0  -1   1   1
  0  -1  -1  -1   0   0   1  -1   0   0   0   1   0  -1   0   1   0   1   1  -1
  0  -1   1   0   0   1  -1  -1   0   1  -1  -1   0  -1   1   0   0   1  -1  -1
  0   0   1  -1   0   1   1   1   0  -1   0   1   0   1   1   1   0  -1   0   0
  0  -1  -1  -1   0  -1   1  -1   0  -1  -1   1   0  -1  -1   1   0   0   1   1
  0   0   1   1   0   0   0  -1   0   1  -1  -1   0   1   1   0   0  -1  -1  -1
  0   1   1   1   0   1   1   0   0  -1   0  -1   0   0  -1   1   0  -1   1   1
  0   1   0  -1   0  -1   1  -1   0   0  -1   0   0  -1  -1   0   0   1   1  -1
  0  -1  -1   1   0   1  -1   1   0   0  -1  -1   0  -1   1  -1   0  -1   0  -1