%I A097112
%S A097112 1,4,13,40,157,400,1813,4000,20317,40000,222853,400000,2405677,4000000,
%T A097112 25651093,40000000,270859837,400000000,2837738533,4000000000,
%U A097112 29539646797,40000000000,305856821173,400000000000,3152711390557
%N A097112 Expansion of (1+4x-6x^2-36x^3)/(1-19x^2+90x^4).
%F A097112 G.f. : 4(1+x)/(1-10x^2)-3/(1-9x^2); a(n)=19a(n-2)-90a(n-4); a(n)=(2+sqrt(10)/
               5)(sqrt(10))^n+(2-sqrt(10)/5)(-sqrt(10))^n-3^(n+1)(1+(-1)^n)/2; a(n)=sum{k=0..n, 
               binomial(floor(n/2), floor(k/2))3^k }
%Y A097112 Sequence in context: A094628 A034742 A149424 this_sequence A077284 A070428 
               A052529
%Y A097112 Adjacent sequences: A097109 A097110 A097111 this_sequence A097113 A097114 
               A097115
%K A097112 easy,nonn
%O A097112 0,2
%A A097112 Paul Barry (pbarry(AT)wit.ie), Jul 25 2004