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%I #6 Jun 13 2015 00:51:54
%S 1,-1,2,0,3,3,8,12,25,43,82,148,275,503,928,1704,3137,5767,10610,
%T 19512,35891,66011,121416,223316,410745,755475,1389538,2555756,
%U 4700771,8646063,15902592,29249424,53798081,98950095,181997602,334745776,615693475,1132436851,2082876104,3831006428
%N Diagonal sums of Riordan array (1/(1+x),x(1+x)/(1-x)).
%C Diagonal sums of A112475.
%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,2,2,1).
%F G.f.: (1-x)/((1+x)(1-x-x^2-x^3)); a(n)=2a(n-2)+2a(n-3)+a(n-4); a(n)=sum{k=0..floor(n/2), sum{j=0..n-2k, C(k-1, j)C(n-k-j-1, n-2k-j)}.
%K easy,sign
%O 0,3
%A _Paul Barry_, Sep 07 2005
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