|
%I #20 Sep 07 2017 07:34:56
%S 1,2,5,9,16,25,39,56,79,107,142,183,233,290,357,433,520,617,727,848,
%T 983,1131,1294,1471,1665,1874,2101,2345,2608,2889,3191,3512,3855,4219,
%U 4606,5015,5449,5906
%N Expansion of (1+x^2)(1+x^4)/((1-x)^2*(1-x^2)*(1-x^3)).
%H Vincenzo Librandi, <a href="/A007979/b007979.txt">Table of n, a(n) for n = 0..1000</a>
%H A. R. Calderbank and N. J. A. Sloane, Double circulant codes over Z_4, J. Algeb. Combin., 6 (1997) 119-131 (<a href="http://neilsloane.com/doc/mckay.txt">Abstract</a>, <a href="http://neilsloane.com/doc/mckay.pdf">pdf</a>, <a href="http://neilsloane.com/doc/mckay.ps">ps</a>).
%H <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (2,0,-1,-1,0,2,-1).
%F a(n) = floor((2*n^3+3*n^2+24*n+18)/18). - _Tani Akinari_, Jun 26 2013
%F G.f.: (1+x^2)*(1+x^4) / ( (1+x)*(1+x+x^2)*(x-1)^4 ). - _R. J. Mathar_, Sep 07 2017
%t CoefficientList[Series[(1+x^2)(1+x^4)/((1-x)^2*(1-x^2)*(1-x^3)),{x,0,40}],x] (* _Vincenzo Librandi_, Feb 25 2012 *)
%K nonn,easy
%O 0,2
%A _N. J. A. Sloane_.
|
