%I A117188
%S A117188 1,0,2,0,1,0,1,0,2,0,1,0,1,0,2,0,1,0,1,0,1,0,2,0,1,0,1,0,2,0,1,0,1,0,2,
%T A117188 0,1,0,1,0,1,0,2,0,1,0,1,0,2,0,1,0,1,0,2,0,1,0,1,0
%V A117188 1,0,-2,0,1,0,1,0,-2,0,1,0,1,0,-2,0,1,0,1,0,1,0,-2,0,1,0,1,0,-2,0,1,0,
               1,0,-2,0,1,0,1,0,
%W A117188 1,0,-2,0,1,0,1,0,-2,0,1,0,1,0,-2,0,1,0,1,0
%N A117188 Expansion of (1-x^2)/(1+x^2+x^4).
%C A117188 Periodic {1,0,-2,0,1,0}. Row sums of A117185.
%F A117188 G.f.: (1-2x^2+x^4)/(1-x^6)
%F A117188 a(n)=(1/6)*{-[n mod 6]+[(n+1) mod 6]-[(n+2) mod 6]-2*[(n+3) mod 6]+2*[(n+4) 
               mod 6]+[(n+5) mod 6]}, with n>=0. - Paolo P. Lava (ppl(AT)spl.at), 
               Jun 01 2007
%Y A117188 Sequence in context: A137277 A039975 A016253 this_sequence A097796 A133565 
               A035169
%Y A117188 Adjacent sequences: A117185 A117186 A117187 this_sequence A117189 A117190 
               A117191
%K A117188 easy,sign
%O A117188 0,3
%A A117188 Paul Barry (pbarry(AT)wit.ie), Mar 01 2006