This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A226303 #14 Nov 04 2019 02:19:15 %S A226303 1,3,4,10,10,22,28,64,76,180,260,606,932,2124,3440,7666,12872,28178, %T A226303 48620,104946,184756,394638,705432,1494600,2704156,5693376,10400600 %N A226303 a(n) = sum of absolute values of coefficients of a certain polynomial P_n(x) arising in the enumeration of tatami mat coverings. %C A226303 See Erickson-Ruskey for precise definition. The polynomials P_n(x) are described as "mysterious". %H A226303 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. %Y A226303 Cf. A226302, A226304. %K A226303 nonn,more %O A226303 2,2 %A A226303 _N. J. A. Sloane_, Jun 06 2013