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 A220581 #6 Jul 23 2025 01:15:02 %S A220581 1,32,91,1441,8334,64497,436288,3036588,21023792,146254012,1011489196, %T A220581 7016643627,48603225482,336693889957,2332461879768,16156948253940, %U A220581 111913294295697,775187951935208,5369332881497134,37190288381188178 %N A220581 Equals one maps: number of 3Xn binary arrays indicating the locations of corresponding elements equal to exactly one of their horizontal and antidiagonal neighbors in a random 0..1 3Xn array. %C A220581 Row 3 of A220579 %H A220581 R. H. Hardin, <a href="/A220581/b220581.txt">Table of n, a(n) for n = 1..27</a> %e A220581 Some solutions for n=3 %e A220581 ..0..0..1....1..1..1....0..0..1....1..0..0....0..1..1....1..0..0....0..0..0 %e A220581 ..1..0..1....1..0..0....1..0..1....0..1..0....1..1..0....0..0..1....0..0..1 %e A220581 ..1..0..0....0..0..1....1..0..1....0..0..0....0..1..1....1..0..1....1..1..0 %K A220581 nonn %O A220581 1,2 %A A220581 _R. H. Hardin_ Dec 16 2012