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 A281721 #4 Jan 28 2017 13:50:47 %S A281721 64,22,30,1625,10738,142023,1721319,18779855,230037168,2667856089, %T A281721 31098469537,368912116468,4299998362349,50615320723942, %U A281721 594638970383925,6971797426746210,81973100282054094,962121842116973906 %N A281721 Number of 7Xn 0..1 arrays with no element unequal to a strict majority of its horizontal, diagonal and antidiagonal neighbors and with new values introduced in order 0 sequentially upwards. %C A281721 Row 7 of A281715. %H A281721 R. H. Hardin, <a href="/A281721/b281721.txt">Table of n, a(n) for n = 1..210</a> %e A281721 Some solutions for n=4 %e A281721 ..0..0..1..1. .0..0..0..0. .0..1..0..1. .0..0..0..0. .0..0..0..1 %e A281721 ..0..0..1..1. .1..1..1..0. .1..0..1..0. .0..0..0..0. .0..0..1..1 %e A281721 ..0..0..1..1. .1..1..0..1. .0..1..0..1. .0..0..0..0. .0..0..1..1 %e A281721 ..0..0..1..1. .0..0..1..0. .0..0..1..0. .1..1..0..0. .0..0..0..1 %e A281721 ..0..0..1..1. .0..0..0..1. .0..0..0..1. .1..1..1..1. .0..0..1..1 %e A281721 ..0..1..1..1. .0..0..1..1. .0..0..1..1. .1..1..1..1. .0..1..1..1 %e A281721 ..0..0..1..1. .0..0..1..1. .0..1..1..1. .1..1..1..1. .1..0..0..0 %Y A281721 Cf. A281715. %K A281721 nonn %O A281721 1,1 %A A281721 _R. H. Hardin_, Jan 28 2017