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%I #14 Jun 16 2016 17:48:41
%S 1,-1,0,1,-2,3,-4,5,-6,7,-8,9,-10,11,-12,13,-14,15,-16,17,-18,19,-20,
%T 21,-22,23,-24,25,-26,27,-28,29,-30,31,-32,33,-34,35,-36,37,-38,39,
%U -40,41,-42,43,-44,45,-46,47,-48,49,-50,51,-52,53,-54,55,-56,57,-58,59,-60,61,-62,63,-64,65
%N Expansion of (1+x-x^2)/(1+x)^2.
%C First column of number triangle A105810.
%H <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (-2,-1).
%F a(n) = -0^n-(-1)^n*(n-2).
%t CoefficientList[Series[(1+x-x^2)/(1+x)^2,{x,0,70}],x] (* or *) LinearRecurrence[ {-2,-1},{1,-1,0},70] (* _Harvey P. Dale_, Jun 16 2016 *)
%o (PARI) a(n)=-0^n-(-1)^n*(n-2) \\ _Charles R Greathouse IV_, Sep 02 2015
%K easy,sign
%O 0,5
%A _Paul Barry_, May 04 2005
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