Search: id:A116404
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%I A116404
%S A116404 1,1,2,6,15,35,84,204,493,1189,2870,6930,16731,40391,97512,235416,
%T A116404 568345,1372105,3312554,7997214,19306983,46611179,112529340,271669860,
%U A116404 655869061,1583407981,3822685022,9228778026,22280241075,53789260175
%N A116404 Expansion of (1-x)/((1-x)^2-x^2(1+x)^2).
%C A116404 Diagonal sums of number triangle A114123. Binomial transform of A114122. 
               Congruent to 1,1,0,0,1,1,... modulo 2.
%F A116404 G.f.: (1-x)/(1-2x-2x^3-x^4); a(n)=2a(n-1)+2a(n-3)+a(n-4); a(n)=sum{k=0..floor(n/
               2), sum{j=0..n-k, C(2k,n-2k-j)*C(n-2k,j)*2^(n-2k-j)}}.
%Y A116404 Sequence in context: A090982 A153517 A136302 this_sequence A084860 A084798 
               A017923
%Y A116404 Adjacent sequences: A116401 A116402 A116403 this_sequence A116405 A116406 
               A116407
%K A116404 easy,nonn
%O A116404 0,3
%A A116404 Paul Barry (pbarry(AT)wit.ie), Feb 07 2006

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