%I #16 Oct 09 2020 03:48:27

%S 0,0,1,2,5,14,40,114,322,900,2490,6826,18564,50146,134690,360068,

%T 958826,2545082,6737860,17799570,46939378,123608388,325130970,

%U 854405962,2243591940,5887904194,15444237890,40495141124,106146043082,278161091930,728790217540,1909149084786,5000603193874,13096687028676,34297779391290

%N G.f.: x^2*(1-x)*(1-4*x+4*x^2+x^3)/((1-2*x)^2*(1-3*x+x^2)).

%H D. Battaglino, J. M. Fedou, S. Rinaldi and S. Socci, <a href="https://hal.inria.fr/hal-01229685">The number of k-parallelogram polyominoes</a>, FPSAC 2013 Paris, France DMTCS Proc. AS, 2013, 1143-1154. hal-01229685.

%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (7,-17,16,-4).

%t CoefficientList[Series[x^2*(1 - x)*(1 - 4*x + 4*x^2 + x^3)/((1 - 2*x)^2*(1 - 3*x + x^2)), {x, 0, 34}], x] (* _Amiram Eldar_, Oct 08 2020 *)

%K nonn,easy

%O 0,4

%A _N. J. A. Sloane_, Oct 04 2013