%I #12 Nov 04 2019 02:19:11
%S 1,1,2,1,1,2,1,1,2,4,0,2,1,0,1,2,2,-2,2,1,0,1,2,2,4,-2,4,0,2,-2,2,1,0,
%T 1,1,2,3,4,-2,2,0,4,-2,2,-2,2,1,0,1,1,2,3,4,6,-2,6,0,8,-2,4,-4,6,-2,4,
%U -2,2,-2,2,1,-1,1,0,1,1,1,2,2,-6,6,-2,6,-6,4,-4,6,-6,6,-4,4,-4,2,1,-1,1,0,1,1,1,2,2,4,-8,10,-4,10,-8,8,-8,10,-10,12,-8,10,-12,10,-6,6,-6,6,-4,4,-4,2
%N Irregular triangle read by rows: coefficients of certain polynomials P_n(x) arising in the enumeration of tatami mat coverings.
%C See Erickson-Ruskey for precise definition. The polynomials P_n(x) are described as "mysterious".
%H Alejandro Erickson, Frank Ruskey, <a href="http://arxiv.org/abs/1304.0070">Enumerating maximal tatami mat coverings of square grids with v vertical dominoes</a>, arXiv:1304.0070 [math.CO], 2013.
%e Triangle begins:
%e 1
%e 1,2
%e 1,1,2
%e 1,1,2,4,0,2
%e 1,0,1,2,2,-2,2
%e 1,0,1,2,2,4,-2,4,0,2,-2,2
%e 1,0,1,1,2,3,4,-2,2,0,4,-2,2,-2,2
%e 1,0,1,1,2,3,4,6,-2,6,0,8,-2,4,-4,6,-2,4,-2,2,-2,2
%e 1,-1,1,0,1,1,1,2,2,-6,6,-2,6,-6,4,-4,6,-6,6,-4,4,-4,2
%e 1,-1,1,0,1,1,1,2,2,4,-8,10,-4,10,-8,8,-8,10,-10,12,-8,10,-12,10,-6,6,-6,6,-4,4,-4,2
%e ...
%Y Cf. A226302, A226303.
%K sign,tabf
%O 2,3
%A _N. J. A. Sloane_, Jun 06 2013