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 A284451 #6 Apr 05 2020 22:59:31 %S A284451 2,0,250,3384,54248,824052,12957944,203401448,3209101642,50702668880, %T A284451 801990075576,12692871462160,200953195066764,3182000912440584, %U A284451 50388819126999402,797940889459632096,12635596604122356028 %N A284451 Number of n X 4 0..1 arrays with the number of 1's king-move adjacent to some 0 one less than the number of 0's adjacent to some 1. %C A284451 Column 4 of A284455. %H A284451 R. H. Hardin, <a href="/A284451/b284451.txt">Table of n, a(n) for n = 1..187</a> %e A284451 Some solutions for n=4 %e A284451 ..1..1..0..0. .0..0..1..1. .1..0..1..0. .0..1..1..1. .1..0..0..1 %e A284451 ..0..0..0..0. .0..0..1..0. .0..1..0..1. .0..1..1..0. .1..0..0..0 %e A284451 ..1..1..0..1. .0..1..0..1. .1..0..0..0. .0..0..0..1. .1..1..0..0 %e A284451 ..0..0..1..1. .1..0..0..1. .1..1..0..0. .0..0..1..0. .1..1..1..0 %Y A284451 Cf. A284455. %K A284451 nonn %O A284451 1,1 %A A284451 _R. H. Hardin_, Mar 27 2017