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 A124342 Expansion of (1+x)/(1+2x-2x^3). 1

%I

%S 1,-1,2,-2,2,0,-4,12,-24,40,-56,64,-48,-16,160,-416,800,-1280,1728,

%T -1856,1152,1152,-6016,14336,-26368,40704,-52736,52736,-24064,-57344,

%U 220160,-488448,862208,-1284096,1591296,-1458176,348160

%N Expansion of (1+x)/(1+2x-2x^3).

%C Diagonal sums of A124341. Binomial transform has g.f. (1-x)/(1-x-x^2-x^3).

%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (-2,0,2).

%F a(n)=sum{k=0..floor(n/2), sum{j=0..n-k, (-1)^(n-k-j)*C(n-k,j)*C(k,j-k)}}

%F a(n) = (-1)^(n+1)*A073358(n+1). - _R. J. Mathar_, Feb 04 2014

%F a(n) = A077988(n-1)+A077988(n). - _R. J. Mathar_, Jan 25 2016

%K easy,sign

%O 0,3

%A _Paul Barry_, Oct 26 2006

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Last modified September 22 17:04 EDT 2019. Contains 327311 sequences. (Running on oeis4.)