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%I #20 Jun 13 2015 00:53:44
%S 1,0,1,-1,1,-1,2,-1,2,-2,2,-2,3,-2,3,-3,3,-3,4,-3,4,-4,4,-4,5,-4,5,-5,
%T 5,-5,6,-5,6,-6,6,-6,7,-6,7,-7,7,-7,8,-7,8,-8,8,-8,9,-8,9,-9,9,-9,10,
%U -9,10,-10,10,-10,11
%N Diagonal sums of number triangle A187034.
%C Absolute values appear to be given (with the same offset) by A103221. - _Jason Kimberley_, Oct 17 2011
%H <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (0,1,-1,0,1).
%F Conjectured: G.f. 1/( (1-x)*(1-x+x^2)*(1+x)^2 ) with a(n) = +a(n-2) -a(n-3) +a(n-5). - R. J. Mathar, Jun 30 2011
%F The above conjecture is correct. [_Charles R Greathouse IV_, Dec 28 2011]
%o (PARI) a(n)=(-1)^n*(n\2-(n-1)\3) \\ _Charles R Greathouse IV_, Dec 28 2011
%K sign,easy
%O 0,7
%A _Paul Barry_, Mar 08 2011
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