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%I #8 Jun 29 2021 15:22:35
%S 0,0,0,1,2,4,6,10,16,27,44,72,116,188,304,493,798,1292,2090,3382,5472,
%T 8855,14328,23184,37512,60696,98208,158905,257114,416020,673134,
%U 1089154,1762288,2851443,4613732,7465176
%N a(n) = (A000045(n)-A173432(n))/2.
%C Also the NW-SE diagonal sums of A173402.
%H <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (2,0,-2,2,0,-1).
%F a(n) + A173433(n) = A000045(n).
%F a(n)= 2*a(n-1) -2*a(n-3) +2*a(n-4) -a(n-6). - _R. J. Mathar_, Mar 01 2010
%F G.f.: x^4 / ( (x-1)*(1+x)*(x^2-x+1)*(x^2+x-1) ). - _R. J. Mathar_, Nov 03 2016
%t CoefficientList[Series[x^4/((x-1)(1+x)(x^2-x+1)(x^2+x-1)),{x,0,40}],x] (* or *) LinearRecurrence[{2,0,-2,2,0,-1},{0,0,0,0,1,2},40] (* _Harvey P. Dale_, Jun 29 2021 *)
%Y Cf. A112468, A000045, A173398, A173402
%K nonn,easy
%O 1,5
%A _Mark Dols_, Feb 18 2010