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 A093654 #4 Mar 30 2012 18:36:40 %S A093654 1,1,1,1,0,1,2,1,2,1,1,0,0,0,1,2,1,0,0,2,1,2,0,1,0,2,0,1,7,2,4,1,7,2, %T A093654 4,1,1,0,0,0,0,0,0,0,1,2,1,0,0,0,0,0,0,2,1,2,0,1,0,0,0,0,0,2,0,1,7,2, %U A093654 4,1,0,0,0,0,7,2,4,1,2,0,0,0,1,0,0,0,2,0,0,0,1,7,2,0,0,4,1,0,0,7,2,0,0,4,1 %N A093654 Lower triangular matrix, read by rows, defined as the convergent of the concatenation of matrices using the iteration: M(n+1) = [[M(n),0*M(n)],[M(n)^2,M(n)^2]], with M(0) = [1]. %C A093654 Related to the number of tournament sequences (A008934). First column forms A093655, where A093655(2^n) = A008934(n) for n>=0. Row sums form A093656, where A093656(2^(n-1)) = A093657(n) for n>=1. %F A093654 First column: T(2^n, 1) = A008934(n) for n>=0. %e A093654 Let M(n) be the lower triangular matrix formed from the first 2^n rows. %e A093654 To generate M(3) from M(2), take the matrix square of M(2): %e A093654 [1,0,0,0]^2=[1,0,0,0] %e A093654 [1,1,0,0]...[2,1,0,0] %e A093654 [1,0,1,0]...[2,0,1,0] %e A093654 [2,1,2,1]...[7,2,4,1] %e A093654 and append M(2)^2 to the bottom left and bottom right of M(2): %e A093654 [1], %e A093654 [1,1], %e A093654 [1,0,1], %e A093654 [2,1,2,1], %e A093654 ......... %e A093654 [1,0,0,0],[1], %e A093654 [2,1,0,0],[2,1], %e A093654 [2,0,1,0],[2,0,1], %e A093654 [7,2,4,1],[7,2,4,1]. %e A093654 Repeating this process converges to triangle A093654. %Y A093654 Cf. A008934, A093655, A093656, A093657, A093658. %K A093654 nonn,tabl %O A093654 1,7 %A A093654 _Paul D. Hanna_, Apr 08 2004