%I A124217
%S A124217 1,1,2,5,11,26,61,143,336,789,1853,4352,10221,24005,56378,132409,310975,
%T A124217 730354,1715305,4028555,9461440,22221081,52188297,122569120,287865097,
%U A124217 676078233,1587833266,3729175645,8758319459,20569736330
%N A124217 Expansion of (1-x-x^2)/(1-2x-x^2+x^4).
%C A124217 Diagonal sums of generalized Pascal triangle A124216.
%F A124217 a(n)=sum{k=0..floor(n/2), sum{j=0..n-k, C(n-k,j)C(j,2(j-k))2^(j-k)}};
%Y A124217 Sequence in context: A026787 A064416 A006138 this_sequence A095981 A082397 
               A051286
%Y A124217 Adjacent sequences: A124214 A124215 A124216 this_sequence A124218 A124219 
               A124220
%K A124217 easy,nonn
%O A124217 0,3
%A A124217 Paul Barry (pbarry(AT)wit.ie), Oct 19 2006