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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.

A223923 Number of 6Xn 0..2 arrays with rows and antidiagonals unimodal and columns nondecreasing.

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%I A223923 #6 Jul 23 2025 04:39:25
%S A223923 28,784,12752,139925,1147712,7526024,41334135,196691651,831996762,
%T A223923 3191126598,11273703656,37147879480,115325935123,340079259419,
%U A223923 958837466287,2598467396144,6797368250655,17222433541791,42380526618210
%N A223923 Number of 6Xn 0..2 arrays with rows and antidiagonals unimodal and columns nondecreasing.
%C A223923 Row 6 of A223918
%H A223923 R. H. Hardin, <a href="/A223923/b223923.txt">Table of n, a(n) for n = 1..210</a>
%F A223923 Empirical: a(n) = (1/35608838483312640000)*n^24 + (1/593480641388544000)*n^23 + (1/11491439984640000)*n^22 + (2153/709596419051520000)*n^21 + (219067/2432902008176640000)*n^20 + (25141/11058645491712000)*n^19 + (7669183/149388719800320000)*n^18 + (2894807/2766457774080000)*n^17 + (345585431/17575143505920000)*n^16 + (19926331/58583811686400)*n^15 + (19845690451/3766102179840000)*n^14 + (29105209667/470762772480000)*n^13 + (9676615094071/17575143505920000)*n^12 + (3447815819587/878757175296000)*n^11 + (1672600520777/75107450880000)*n^10 + (40399178860907/399435079680000)*n^9 + (5902479263543591/16005934264320000)*n^8 + (857508181884829/800296713216000)*n^7 + (1309477651758586831/532197314288640000)*n^6 + (43433412218488139/9855505820160000)*n^5 + (4693314253940149/778066248960000)*n^4 + (1959925243391/320817246750)*n^3 + (12456072565753/2698531355520)*n^2 + (3225389971/1784742960)*n + 1
%e A223923 Some solutions for n=3
%e A223923 ..0..0..0....0..0..0....0..2..1....0..1..1....0..0..0....0..1..0....0..2..0
%e A223923 ..0..1..0....2..1..0....1..2..1....0..1..1....0..1..0....0..1..0....0..2..0
%e A223923 ..0..1..2....2..1..0....1..2..1....0..1..1....0..1..0....0..2..2....0..2..0
%e A223923 ..0..1..2....2..1..0....1..2..2....0..1..2....0..1..0....0..2..2....0..2..0
%e A223923 ..0..2..2....2..1..0....2..2..2....0..1..2....1..1..0....1..2..2....0..2..0
%e A223923 ..1..2..2....2..1..0....2..2..2....0..2..2....1..2..1....1..2..2....1..2..2
%K A223923 nonn
%O A223923 1,1
%A A223923 _R. H. Hardin_ Mar 29 2013