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 A224386 #6 Jul 23 2025 05:08:27 %S A224386 20,400,6094,86701,1268572,18794636,279128617,4142692993,61481903024, %T A224386 912523782542,13544525098266,201041292342421,2984053971336637, %U A224386 44292278131103241,657430060365000621,9758232360460992934 %N A224386 Number of nX3 0..3 arrays with diagonals and antidiagonals unimodal and rows nondecreasing. %C A224386 Column 3 of A224391 %H A224386 R. H. Hardin, <a href="/A224386/b224386.txt">Table of n, a(n) for n = 1..210</a> %F A224386 Empirical: a(n) = 20*a(n-1) -70*a(n-2) -211*a(n-3) +2453*a(n-4) -12192*a(n-5) +5907*a(n-6) +119292*a(n-7) -294992*a(n-8) +742820*a(n-9) +144828*a(n-10) -5072952*a(n-11) +6034728*a(n-12) -15994872*a(n-13) -858096*a(n-14) -10368*a(n-15) %e A224386 Some solutions for n=3 %e A224386 ..0..2..3....0..0..3....0..0..0....0..0..0....1..1..2....1..3..3....1..1..3 %e A224386 ..0..3..3....0..2..2....3..3..3....1..1..2....0..3..3....1..2..2....1..1..1 %e A224386 ..0..3..3....2..2..3....0..1..3....0..0..2....1..1..1....1..1..2....1..3..3 %K A224386 nonn %O A224386 1,1 %A A224386 _R. H. Hardin_ Apr 05 2013