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 A221293 #5 Jul 23 2025 01:49:33 %S A221293 1,114,3332,123958,4983598,172905144,6138441061 %N A221293 Equals two maps: number of 5Xn binary arrays indicating the locations of corresponding elements equal to exactly two of their horizontal and antidiagonal neighbors in a random 0..3 5Xn array. %C A221293 Row 5 of A221290 %e A221293 Some solutions for n=3 %e A221293 ..0..0..1....0..0..0....0..0..0....0..0..1....0..1..0....0..1..0....0..1..1 %e A221293 ..0..0..0....0..1..0....0..0..1....1..0..0....1..0..1....0..0..0....1..0..1 %e A221293 ..0..1..0....1..1..0....1..0..0....0..0..0....1..0..1....0..0..0....1..1..0 %e A221293 ..0..1..1....1..0..0....0..1..1....1..1..0....1..0..1....1..0..1....0..1..1 %e A221293 ..0..0..0....0..0..0....1..0..0....1..0..0....0..1..0....1..1..0....1..0..0 %K A221293 nonn %O A221293 1,2 %A A221293 _R. H. Hardin_ Jan 09 2013