%I A097115
%S A097115 1,11,111,1111,12211,112211,1333311,11333311,144664411,1144664411,
%T A097115 15611105511,115611105511,1676721656611,11676721656611,179348887317711,
%U A097115 1179348887317711,19114237619088811,119114237619088811
%N A097115 Expansion of (1+11x-90x^2-1100x^3)/(1-201x^2+10100x^4).
%F A097115 G.f. : 11(1+x)/(1-101x^2)-10/(1-100x^2); a(n)=201a(n-2)-10100a(n-2); 
               a(n)=(11/2+11sqrt(101)/202)sqrt(101)^n+(11/2-11sqrt(101)/202)(-sqrt(101))^n-10^(n+1)(1+(-1)^n)/
               2; a(n)=sum{k=0..n, binomial(floor(n/2), floor(k/2))10^k }.
%Y A097115 Sequence in context: A002275 A078998 A078191 this_sequence A134732 A166747 
               A015456
%Y A097115 Adjacent sequences: A097112 A097113 A097114 this_sequence A097116 A097117 
               A097118
%K A097115 easy,nonn
%O A097115 0,2
%A A097115 Paul Barry (pbarry(AT)wit.ie), Jul 25 2004