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 A225980 #6 Jul 23 2025 05:26:03 %S A225980 42,790,16361,361361,7718077,148890101,2513743785,36836074434, %T A225980 470279869497,5279223820491,52686610737385,472630223607623, %U A225980 3849896640784837,28735919289705656,198113452132002555 %N A225980 Number of nX6 binary arrays whose sum with another nX6 binary array containing no more than two 1s has rows and columns in lexicographically nondecreasing order. %C A225980 Column 6 of A225982 %H A225980 R. H. Hardin, <a href="/A225980/b225980.txt">Table of n, a(n) for n = 1..29</a> %e A225980 Some solutions for n=3 %e A225980 ..0..0..1..1..1..1....0..0..0..0..0..1....0..0..0..0..1..1....0..0..0..1..1..1 %e A225980 ..1..0..0..0..0..1....0..1..0..0..1..0....0..1..0..0..0..0....0..0..0..0..0..1 %e A225980 ..1..0..1..0..1..0....1..0..1..1..1..1....1..0..0..0..1..1....0..1..0..1..1..0 %K A225980 nonn %O A225980 1,1 %A A225980 _R. H. Hardin_ May 22 2013