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 A225783 #41 Nov 30 2014 14:57:05 %S A225783 0,1,0,0,2,0,0,0,0,15,0,0,4,0,1,0,0,0,0,0,0,0,0,0,0,8,0,0,0,0,0,0,0, %T A225783 63,0,0,0,0,0,0,0,0,0,0,240,0,0,0,0,0,0,0,0,0,0,0,0,0,0,6,0,112,0,0,0, %U A225783 36,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,63,0,0,0,0,0,0,0,0,0,0,0,0,0,15,0,0,0,0,0,0 %N A225783 Triangle read by rows: T(n,m) is the number of n X m binary (0,1) matrices that represent perfect parity patterns. %C A225783 An n X m matrix of zeros and ones is perfect if no row or column consists entirely of zeros (as counted in A183109). It is a parity pattern if every 0 is adjacent (vertically or horizontally) to an even number of 1s and every 1 is adjacent to an odd number of 1s. %H A225783 R. J. Mathar, <a href="/A225783/b225783.txt">Table of n, a(n) for n = 1..106</a> %H A225783 R. Chapman, D. E. Knuth, <a href="http://www.jstor.org/stable/27642574">Problem 11243, Perfect parity patterns</a>, Am. Math. Monthly 115 (7) (2008) p 668. %H A225783 R. J. Mathar, <a href="/A225783/a225783.pdf">Discussion and JAVA source code</a> %e A225783 The T(5,3) = 4 perfect parity 5 X 3 patterns are %e A225783 0 0 1 %e A225783 0 1 1 %e A225783 1 0 1 %e A225783 1 1 0 %e A225783 1 0 0 %e A225783 ------ %e A225783 0 1 1 %e A225783 1 0 0 %e A225783 1 0 1 %e A225783 0 0 1 %e A225783 1 1 0 %e A225783 -------- %e A225783 1 0 0 %e A225783 1 1 0 %e A225783 1 0 1 %e A225783 0 1 1 %e A225783 0 0 1 %e A225783 -------- %e A225783 1 1 0 %e A225783 0 0 1 %e A225783 1 0 1 %e A225783 1 0 0 %e A225783 0 1 1 %K A225783 nonn,tabl %O A225783 1,5 %A A225783 _R. J. Mathar_, Jun 13 2014