%I A117441
%S A117441 1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,
%T A117441 0
%V A117441 1,1,0,1,-1,0,-1,-1,0,-1,1,0,1,1,0,1,-1,0,-1,-1,0,-1,1,0,1,1,0,1,-1,0,
               -1,-1,0,-1,1,0
%N A117441 Periodic with period {1,1,0,1,-1,0,-1,-1,0,-1,1,0}.
%C A117441 Diagonal sums of number triangle A117440.
%F A117441 G.f.: (1+x-x^2)/(1-x^2+x^4); a(n)=sum{k=0..floor(n/2), C(n-k,k)*(cos(pi*(n-2k)/
               2)+sin(pi*(n-2k)/2)}.
%F A117441 a(n)=(1/12)*{-(n mod 12)+[(n+1) mod 12]-2*[(n+2) mod 12]+[(n+3) mod 12]-[(n+4) 
               mod 12]+[(n+6) mod 12]-[(n+7) mod 12]+2*[(n+8) mod 12]-[(n+9) mod 
               12]+[(n+10) mod 12]}, with n>=0 - Paolo P. Lava (ppl(AT)spl.at), 
               Jun 11 2007
%Y A117441 Sequence in context: A016118 A011646 A016350 this_sequence A049347 A010892 
               A091338
%Y A117441 Adjacent sequences: A117438 A117439 A117440 this_sequence A117442 A117443 
               A117444
%K A117441 easy,sign,more
%O A117441 0,1
%A A117441 Paul Barry (pbarry(AT)wit.ie), Mar 16 2006