%I A120581
%S A120581 1,4,64,28672,17825792,24696061952,4398046511104,6413125869375586304,
%T A120581 1279761316857673852911616,565738597953418785628899770368,
%U A120581 372547299599873882347063111621541888,5264848781000759906705331926184317767647232
%V A120581 1,4,-64,-28672,-17825792,-24696061952,-4398046511104,6413125869375586304,
%W A120581 1279761316857673852911616,565738597953418785628899770368,
%X A120581 372547299599873882347063111621541888,-5264848781000759906705331926184317767647232
%N A120581 Hankel transform of sum{k=0..n, C(2k,k)*2^k}.
%F A120581 a(n)=4^(n+C(n,2))(-1)^n*sum{k=0..n, C(n+k,2k)(-2)^(n-k)}; a(n)=8^n*4^C(n,
               2)*sum{k=0..n, C(n+k,2k)(-2)^(-k)}; a(n)=4^n*4^C(n,2)(-1)^n*A087168(n);
%Y A120581 Cf. A120580.
%Y A120581 Sequence in context: A053763 A053923 A051191 this_sequence A146520 A030176 
               A033635
%Y A120581 Adjacent sequences: A120578 A120579 A120580 this_sequence A120582 A120583 
               A120584
%K A120581 easy,sign
%O A120581 0,2
%A A120581 Paul Barry (pbarry(AT)wit.ie), Jun 15 2006