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 A224404 #8 Aug 30 2018 06:07:34 %S A224404 7,28,100,358,1288,4636,16684,60040,216064,777544,2798128,10069552, %T A224404 36237040,130405312,469286272,1688808544,6077472256,21870844480, %U A224404 78706050496,283237457536,1019279418112,3668054858368,13200135512320 %N A224404 Number of n X 3 0..1 arrays with rows unimodal and antidiagonals nondecreasing. %C A224404 Column 3 of A224409. %H A224404 R. H. Hardin, <a href="/A224404/b224404.txt">Table of n, a(n) for n = 1..210</a> %F A224404 Empirical: a(n) = 4*a(n-1) - 2*a(n-2) + 2*a(n-3). %F A224404 Empirical g.f.: x*(7 + 2*x^2) / (1 - 4*x + 2*x^2 - 2*x^3). - _Colin Barker_, Aug 30 2018 %e A224404 Some solutions for n=3: %e A224404 ..0..1..0....0..0..0....1..1..0....1..1..0....0..0..0....0..1..0....0..0..1 %e A224404 ..1..1..0....0..0..0....1..1..1....1..0..0....0..1..0....1..0..0....1..1..0 %e A224404 ..1..0..0....0..0..1....1..1..0....0..0..0....1..1..1....0..1..1....1..1..0 %Y A224404 Cf. A224409. %K A224404 nonn %O A224404 1,1 %A A224404 _R. H. Hardin_, Apr 05 2013