%I A053864
%S A053864 1,1,1,1,1,1,1,0,1,1,1,1,1,1,1,0,1,1,1,1,1,1,1,0,1,1,0,1,1,1,1,
%T A053864 0,1,1,1,1,1,1,1,0,1,1,1,1,1,1,1,0,1,1,1,1,1,0,1,0,1,1,1,1,1,1,
%U A053864 1,0,1,1,1,1,1,1,1,0,1,1,1,1,1,1,1,0,0,1,1,1,1,1,1,0,1,1,1,1,1
%V A053864 1,1,1,-1,1,1,1,0,-1,1,1,1,1,1,1,0,1,1,1,1,1,1,1,0,-1,1,0,1,1,1,1,
%W A053864 0,1,1,1,1,1,1,1,0,1,1,1,1,1,1,1,0,-1,1,1,1,1,0,1,0,1,1,1,1,1,1,
%X A053864 1,0,1,1,1,1,1,1,1,0,1,1,1,1,1,1,1,0,0,1,1,1,1,1,1,0,1,1,1,1,1
%N A053864 Mobius (or Moebius) function of order 2, mu_2(n).
%D A053864 T. M. Apostol, Introduction to Analytic Number Theory, Springer-Verlag, 
               1976, page 50.
%p A053864 with(numtheory); k := 2; A053864 := proc(n,k) local t1,t2,i; t1 := 1; 
               if n=1 then RETURN(t1); fi; t2 := factorset(n); for i in t2 do if 
               n mod i^(k+1) = 0 then RETURN(0); fi; od; for i in t2 do if n mod 
               i^k <> 0 then RETURN(1); else t1 := -t1; fi; od; t1; end;
%Y A053864 Cf. A008683, A053865, A053981.
%Y A053864 Sequence in context: A118111 A119981 A115789 this_sequence A129667 A071374 
               A077010
%Y A053864 Adjacent sequences: A053861 A053862 A053863 this_sequence A053865 A053866 
               A053867
%K A053864 sign
%O A053864 1,1
%A A053864 N. J. A. Sloane (njas(AT)research.att.com), Apr 08 2000