%I A104537
%S A104537 1,1,2,8,8,16,64,64,128,512,512,1024,4096,4096,8192,32768,32768,65536,
%T A104537 262144,262144,524288,2097152,2097152,4194304,16777216,16777216,33554432,
%U A104537 134217728,134217728,268435456,1073741824,1073741824,2147483648,8589934592
%V A104537 1,-1,-2,8,-8,-16,64,-64,-128,512,-512,-1024,4096,-4096,-8192,32768,-32768,
               -65536,
%W A104537 262144,-262144,-524288,2097152,-2097152,-4194304,16777216,-16777216,-33554432,
%X A104537 134217728,-134217728,-268435456,1073741824,-1073741824,-2147483648,8589934592
%N A104537 Expansion of (1+x)/(1+2x+4x^2).
%C A104537 a(n+1) is the Hankel transform of C(2n,n)-C(2n+2,n+1). - Paul Barry (pbarry(AT)wit.ie), 
               Mar 14 2008
%C A104537 a(n+1) is the Hankel transform of C(2n,n)-2*C(n)=((n-1)/(n+1))*C(2n,n), 
               where C(n)=A000108(n). - Paul Barry (pbarry(AT)wit.ie), Mar 14 2008
%F A104537 a(n)=-2a(n-1)-4a(n-2); a(n)=2^n*cos(2*pi*n/3).
%F A104537 a(n)=Sum_{k, 0<=k<=n}A098158(n,k)*(-1)^k*3^(n-k). [From Philippe DELEHAM 
               (kolotoko(AT)wanadoo.fr), Nov 14 2008]
%F A104537 a(n)=(1/2)*{[ -1+I*sqrt(3)]^n+[ -1-I*sqrt(3)]^n}, with n>=0 [From Paolo 
               P. Lava (ppl(AT)spl.at), Nov 19 2008]
%Y A104537 Sequence in context: A079458 A138230 A128018 this_sequence A019240 A093907 
               A116471
%Y A104537 Adjacent sequences: A104534 A104535 A104536 this_sequence A104538 A104539 
               A104540
%K A104537 easy,sign
%O A104537 0,3
%A A104537 Paul Barry (pbarry(AT)wit.ie), Mar 13 2005