%I A120630
%S A120630 1,1,0,0,2,0,0,0,1,2,0,0,2,0,0,0,2,1,0,0,0,0,0,0,1,2,0,0,2,0,0,0,0,2,0,
               0,2,0,0,
%T A120630 0,2,0,0,0,2,0,0,0,1,1,0,0,2,0,0,0,0,2,0,0,2,0,0,0,4,0,0,0,0,0,0,0,2,2,
               0,0,0,0,0,
%U A120630 0,0,2,0,0,4,0,0,0,2,2,0,0,0,0,0,0,2,1,0,0,2,0,0,0,0,2,0,0,2,0,0,0,2,0,
               0,0,2,0,0
%V A120630 1,-1,0,0,-2,0,0,0,-1,2,0,0,-2,0,0,0,-2,1,0,0,0,0,0,0,1,2,0,0,-2,0,0,0,
               0,2,0,0,-2,0,0,
%W A120630 0,-2,0,0,0,2,0,0,0,-1,-1,0,0,-2,0,0,0,0,2,0,0,-2,0,0,0,4,0,0,0,0,0,0,
               0,-2,2,0,0,0,0,0,
%X A120630 0,0,2,0,0,4,0,0,0,-2,-2,0,0,0,0,0,0,-2,1,0,0,-2,0,0,0,0,2,0,0,-2,0,0,
               0,-2,0,0,0,2,0,0
%N A120630 Dirichlet inverse of A002654.
%F A120630 Multiplicative function with a(p^e)=0 if e>2. a(2)=-1, a(4)=0. If p is 
               a prime congruent to 3 modulo 4, then a(p)=0 and a(p^2)=-1. If p 
               is a prime congruent to 1 modulo 4, then a(p)=-2 and a(p^2)=1.
%e A120630 a(65)=4 because 65 is 5 times 13 and both of those primes are congruent 
               to 1 modulo 4. Doubling an odd index yields the opposite of the value 
               (e.g., a(130)=-4) because a(2)=-1. Doubling an even index yields 
               zero.
%Y A120630 Cf. A002654, A023900, A046692, A053822, A053825, A053826, A101035.
%Y A120630 Sequence in context: A132406 A079126 A025891 this_sequence A089605 A060016 
               A117408
%Y A120630 Adjacent sequences: A120627 A120628 A120629 this_sequence A120631 A120632 
               A120633
%K A120630 mult,easy,sign
%O A120630 1,5
%A A120630 Gerard P. Michon (g.michon(AT)att.net), Jun 25 2006