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 A224140 #8 Jul 23 2025 05:00:39 %S A224140 2,9,49,272,1509,8375,46586,259927,1454873,8167578,45975525,259412481, %T A224140 1466771294,8308711329,47142516717,267868554552,1524033271457, %U A224140 8681096155047,49500982033342,282533898125471,1614019099745197 %N A224140 Number of n X n 0..1 arrays with rows and antidiagonals unimodal and columns nondecreasing. %C A224140 Diagonal of A224146 %H A224140 R. H. Hardin, <a href="/A224140/b224140.txt">Table of n, a(n) for n = 1..22</a> %e A224140 Some solutions for n=3 %e A224140 ..1..1..1....0..1..0....0..1..1....1..0..0....0..0..0....0..0..0....0..0..0 %e A224140 ..1..1..1....0..1..0....0..1..1....1..0..0....0..0..0....1..1..0....0..0..0 %e A224140 ..1..1..1....0..1..1....0..1..1....1..1..0....1..1..1....1..1..1....0..0..0 %K A224140 nonn %O A224140 1,1 %A A224140 _R. H. Hardin_ Mar 31 2013