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 A224199 #6 Jul 23 2025 05:02:36 %S A224199 50,984,16060,263516,4357084,72105068,1193130640,19742052632, %T A224199 326659600368,5405039750704,89433956076272,1479810123371280, %U A224199 24485531969701600,405147434704078656,6703731985610244736 %N A224199 Number of nX3 0..3 arrays with rows unimodal and antidiagonals nondecreasing. %C A224199 Column 3 of A224204 %H A224199 R. H. Hardin, <a href="/A224199/b224199.txt">Table of n, a(n) for n = 1..210</a> %F A224199 Empirical: a(n) = 20*a(n-1) -70*a(n-2) +228*a(n-3) -276*a(n-4) +392*a(n-5) -196*a(n-6) +144*a(n-7) %e A224199 Some solutions for n=3 %e A224199 ..0..0..1....0..0..2....1..2..3....1..0..0....0..2..2....0..0..2....3..0..0 %e A224199 ..0..1..3....2..3..0....2..3..0....3..3..2....3..2..2....3..2..2....2..0..0 %e A224199 ..1..3..1....3..0..0....3..2..2....3..3..0....3..2..1....2..3..2....0..1..1 %K A224199 nonn %O A224199 1,1 %A A224199 _R. H. Hardin_ Apr 01 2013