Editing Möbius function (section)

===<math>\mu(n)</math> sections===
<math>\mu(n)=0</math> [[if and only if]] <math>n</math> is divisible by the square of a prime. The first numbers with this property are

:4, 8, 9, 12, 16, 18, 20, 24, 25, 27, 28, 32, 36, 40, 44, 45, 48, 49, 50, 52, 54, 56, 60, 63, ... {{OEIS|id=A013929}}.

If <math>n</math> is prime, then <math>\mu(n)=-1</math>, but the converse is not true. The first non prime <math>n</math> for which <math>\mu(n)=-1</math> is <math> 30 = 2\times 3\times 5</math>. The first such numbers with three distinct prime factors ([[sphenic number]]s) are

:30, 42, 66, 70, 78, 102, 105, 110, 114, 130, 138, 154, 165, 170, 174, 182, 186, 190, 195, 222, ... {{OEIS|id=A007304}}.

and the first such numbers with 5 distinct prime factors are

:2310, 2730, 3570, 3990, 4290, 4830, 5610, 6006, 6090, 6270, 6510, 6630, 7410, 7590, 7770, 7854, 8610, 8778, 8970, 9030, 9282, 9570, 9690, ... {{OEIS|id=A046387}}.