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 A220329 #6 Jul 23 2025 01:03:54 %S A220329 1,4,16,48,174,658,2482,9229,33982,125217,461351,1699127,6252129, %T A220329 22995280,84546207,310785413,1142206689,4197260747,15421867303, %U A220329 56659522539,208152496049,764662949438,2808941077111,10318186228202 %N A220329 Equals two maps: number of 2Xn binary arrays indicating the locations of corresponding elements equal to exactly two of their horizontal and antidiagonal neighbors in a random 0..1 2Xn array. %C A220329 Row 2 of A220328 %H A220329 R. H. Hardin, <a href="/A220329/b220329.txt">Table of n, a(n) for n = 1..210</a> %e A220329 Some solutions for n=3 %e A220329 ..0..1..0....0..0..1....0..0..0....0..0..1....0..1..1....0..1..1....0..1..0 %e A220329 ..0..0..0....1..0..0....0..1..0....0..0..0....0..1..0....1..1..0....1..1..0 %K A220329 nonn %O A220329 1,2 %A A220329 _R. H. Hardin_ Dec 10 2012