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 A134265 #4 Mar 30 2012 17:34:22
%S A134265 1,1,-1,1,-2,1,1,2,-1,-2,1,1,-2,-7,6,20,6,-7,-2,1,1,2,-25,-10,225,
%T A134265 -184,-498,500,610,-500,-498,184,225,10,-25,-2,1
%N A134265 Coefficients of the polynomials of a three level Hadamard matrix substitution set based on the game matrix set: MA={{0,1},{1,1}};MB={{1,0},{3,1}} Substitution rule is for m[n]:If[m[n - 1][[i, j]] == 0, {{0, 0}, {0, 0}}, If[m[n - 1][[i, j]] == 1, MA, MB]] Based on the Previte idea of graph substitutions as applied to matrices of graphs in the Fibonacci/ anti-Fibonacci game.
%C A134265 m[n_] := Table[Table[If[m[n - 1][[i, j]] == 0, {{0, 0}, {0, 0}}, If[m[n - 1][[i, j]] == 1, ma, {{1, 0}, {3, 1}}]], {j, 1, 2^(n - 1)}], {i, 1, 2^(n - 1)}]
%C A134265 Michelle Previte and Sean Yang say Have you ever wanted to build your own fractal? This article will describe a procedure called a vertex replacement rule that can be used to construct fractals. We also show how one can easily compute the topological and box dimensions of the fractals resulting from vertex replacements.
%H A134265 Michelle Previte and Sean Yang, <a href="http://www.maa.org/pubs/monthly_jan08_toc.html">A Novel Way to Generate Fractals</a>
%F A134265 m[n] = If[m[n - 1][[i, j]] == 0, {{0, 0}, {0, 0}}, If[m[n - 1][[i, j]] == 1, MA, MB]] m[0] = {{1}} m[1] = {{1, 0}, {3, 1}} m[2] = {{0, 1, 0, 0}, {1, 1, 0, 0}, {1, 0, 0, 1}, {3, 1, 1, 1}} m[3] = {{0, 0, 0, 1, 0, 0, 0, 0}, {0, 0, 1, 1, 0, 0, 0, 0}, {0, 1, 0, 1, 0, 0, 0, 0}, {1, 1, 1, 1, 0, 0, 0, 0}, {0, 1, 0, 0, 0, 0, 0, 1}, {1, 1, 0, 0, 0, 0, 1, 1}, {1, 0, 0, 1, 0, 1, 0, 1}, {3, 1, 1, 1, 1, 1, 1, 1}} m[4] = {{0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0}, {0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0}, {0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0}, {0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0}, {0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0}, {0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0}, {0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0}, {1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0}, {0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1}, {0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1}, {0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1}, {1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1}, {0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1}, {1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1}, {1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1}, {3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}}
%e A134265 {1},
%e A134265 {1, -1},
%e A134265 {1, -2, 1},
%e A134265 {1, 2, -1, -2, 1},
%e A134265 {1, -2, -7, 6, 20, 6, -7, -2,1},
%e A134265 {1, 2, -25, -10, 225, -184, -498, 500, 610, -500, -498,184, 225, 10, -25, -2, 1}
%t A134265 m[0] = {{1}} m[1] = {{1, 0}, {3, 1}} m[2] = {{0, 1, 0, 0}, {1, 1, 0, 0}, {1, 0, 0, 1}, {3, 1, 1, 1}} m[3] = {{0, 0, 0, 1, 0, 0, 0, 0}, {0, 0, 1, 1, 0, 0, 0, 0}, {0, 1, 0, 1, 0, 0, 0, 0}, {1, 1, 1, 1, 0, 0, 0, 0}, {0, 1, 0, 0, 0, 0, 0, 1}, {1, 1, 0, 0, 0, 0, 1, 1}, {1, 0, 0, 1, 0, 1, 0, 1}, {3, 1, 1, 1, 1, 1, 1, 1}} m[4] = {{0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0}, {0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0}, {0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0}, {0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0}, {0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0}, {0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0}, {0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0}, {1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0}, {0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1}, {0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1}, {0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1}, {1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1}, {0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1}, {1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1}, {1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1}, {3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}}; Table[CharacteristicPolynomial[m[i], x], {i, 0, 4}]; a = Join[{{1}}, Table[CoefficientList[CharacteristicPolynomial[m[i], x], x], {i, 0, 4}]]; Flatten[a] (* visualization*) Table[ListDensityPlot[m[i]], {i, 0, 4}]
%Y A134265 Cf. A122947, A131218.
%K A134265 tabf,uned,sign
%O A134265 1,5
%A A134265 _Roger L. Bagula_, Jan 24 2008