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%I #13 Oct 02 2023 14:34:21
%S 1,1,-3,9,-11,1,45,-135,229,-143,-483,2025,-4139,4321,3597,-28071,
%T 69829,-97199,12285,351945,-1104971,1907137,-1301523,-3723975,
%U 16378021,-34238159,37202397,25345449,-224845931,573156001,-820084275,167628825,2777450629,-9002867183
%N Expansion of g.f. (1+3*x)/((1-x)*(1+3*x+4*x^2)).
%C Bisection of A107443.
%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (-2, -1, 4).
%F a(n) = (1/2)*(1 - A087168(n+1)).
%o (Magma) a087168:=func< n | &+[ Binomial(n+k, 2*k)*(-2)^(n-k): k in [0..n] ] >; [ (1-a087168(n+1))/2: n in [0..35] ];
%K sign,easy
%O 0,3
%A _Ralf Stephan_, Nov 29 2010
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