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 A224266 #8 Mar 18 2025 22:32:27 %S A224266 28,784,11990,116692,816361,4480391,20568693,82733667,301228048, %T A224266 1015242774,3216158234,9677475342,27865037554,77192516888, %U A224266 206580752375,535811566173,1350500930653,3315175437671,7940967421582,18591190564502,42601309065441,95664964823719,210745412046812 %N A224266 Number of 6 X n 0..2 arrays with rows, diagonals and antidiagonals unimodal and columns nondecreasing. %H A224266 R. H. Hardin, <a href="/A224266/b224266.txt">Table of n, a(n) for n = 1..204</a> %F A224266 Empirical: a(n) = (1/35608838483312640000)*n^24 - (1/989134402314240000)*n^23 + (601/8515157028618240000)*n^22 - (547/425757851430912000)*n^21 + (13921/270322445352960000)*n^20 - (200479/608225502044160000)*n^19 + (115963/6590678814720000)*n^18 + (117617/1244905998336000)*n^17 + (252537361/52725430517760000)*n^16 + (879308299/13181357629440000)*n^15 + (134826737/114124308480000)*n^14 - (85421863/37661021798400)*n^13 + (32134877807171/52725430517760000)*n^12 - (2871377051923/488198430720000)*n^11 + (1288837369490701/13181357629440000)*n^10 - (184837585191797/329533940736000)*n^9 + (23642024191142869/5335311421440000)*n^8 - (12049177715869673/1000370891520000)*n^7 + (510702403798050053/44349776190720000)*n^6 + (72547792289651647/739162936512000)*n^5 - (132132690434377993/149325845760000)*n^4 + (83209134313815637/41064607584000)*n^3 + (10053832694553481/264561897600)*n^2 - (1502154800678423/5354228880)*n + 570714 for n>6. %e A224266 Some solutions for n=3: %e A224266 ..0..0..0....0..0..0....0..0..0....0..1..1....0..0..0....0..0..0....0..0..0 %e A224266 ..0..0..0....0..0..0....0..0..0....0..1..1....0..0..0....1..1..0....0..1..1 %e A224266 ..0..0..1....1..2..0....1..0..0....0..2..1....0..1..1....1..1..0....1..1..2 %e A224266 ..0..0..1....1..2..2....2..0..0....1..2..2....0..1..1....1..1..0....1..1..2 %e A224266 ..0..0..2....2..2..2....2..1..0....2..2..2....1..2..1....2..2..0....1..2..2 %e A224266 ..0..2..2....2..2..2....2..1..1....2..2..2....2..2..2....2..2..0....1..2..2 %Y A224266 Row 6 of A224262. %K A224266 nonn %O A224266 1,1 %A A224266 _R. H. Hardin_, Apr 02 2013 %E A224266 Name corrected by _Andrew Howroyd_, Mar 18 2025