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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.

A224386 Number of nX3 0..3 arrays with diagonals and antidiagonals unimodal and rows nondecreasing.

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%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