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 A269081 #4 Feb 19 2016 08:49:44 %S A269081 128,1760,43959,742688,14011359,236272677,4064720816,67174864630, %T A269081 1109043586715,17995383255288,290431722641261,4645047826683577, %U A269081 73887191299532384,1168678595574438796,18400291710723401503 %N A269081 Number of 7Xn binary arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling two not more than once. %C A269081 Row 7 of A269075. %H A269081 R. H. Hardin, <a href="/A269081/b269081.txt">Table of n, a(n) for n = 1..210</a> %e A269081 Some solutions for n=3 %e A269081 ..1..0..0. .0..0..0. .1..0..1. .1..0..1. .1..0..0. .1..0..1. .0..0..1 %e A269081 ..1..0..0. .0..0..1. .1..0..1. .1..0..0. .0..0..1. .1..0..1. .0..0..1 %e A269081 ..0..0..0. .1..0..0. .1..0..0. .1..0..0. .1..0..0. .0..0..0. .1..0..0 %e A269081 ..1..0..0. .1..0..1. .1..0..0. .0..0..0. .0..0..0. .0..0..0. .1..0..0 %e A269081 ..1..0..1. .1..0..1. .0..0..1. .0..0..0. .0..0..0. .0..0..1. .1..0..0 %e A269081 ..0..0..1. .0..0..0. .0..0..1. .0..0..1. .1..0..1. .0..0..1. .1..0..1 %e A269081 ..0..1..0. .1..0..0. .0..0..1. .1..0..1. .0..0..0. .0..0..1. .0..0..0 %Y A269081 Cf. A269075. %K A269081 nonn %O A269081 1,1 %A A269081 _R. H. Hardin_, Feb 19 2016