%I M0011
%S 2,0,0,1,0,2,0,1,1,2,0,1,0,2,2,1,0,1,0,1,2,2,0,1,1,2,1,1,0,0,0,1,2,2,
%T 2,1,0,2,2,1,0,0,0,1,1,2,0,1,1,1,2,1,0,1,2,1,2,2,0,1,0,2,1,1,2,0,0,1,
%U 2,0,0,1,0,2,1,1,2,0,0,1,1,2,0,1,2,2,2,1,0,1,2,1,2,2,2,1,0,1,1,1
%N mu(n) + 1, where mu is the Moebius function.
%D G. H. Hardy and E. M. Wright, An Introduction to the Theory of Numbers. 3rd ed., Oxford Univ. Press, 1954, p. 234.
%D K. Ireland and M. Rosen, A Classical Introduction to Modern Number Theory. SpringerVerlag, NY, 1982, p. 19.
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H Reinhard Zumkeller, <a href="/A007423/b007423.txt">Table of n, a(n) for n = 1..10000</a>
%p with(numtheory); A007423:=n>mobius(n)+1; seq(A007423(k), k=1..100); # _Wesley Ivan Hurt_, Oct 24 2013
%t MoebiusMu[Range[100]]+1 (* _Harvey P. Dale_, Nov 08 2011 *)
%o (Haskell)
%o a007423 = (+ 1) . a008683  _Reinhard Zumkeller_, Jul 30 2014
%o (PARI) a(n)=moebius(n)+1 \\ _Charles R Greathouse IV_, Feb 25 2018
%Y Cf. A008683.
%Y a(n) = abs(A007423(n))
%K easy,nonn,nice
%O 1,1
%A _N. J. A. Sloane_.
