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 A224263 #10 Mar 18 2025 22:32:43 %S A224263 10,100,648,3096,12032,40182,119367,322885,808618,1898050,4215105, %T A224263 8921265,18101023,35375831,66857059,122591129,218705294,380533212, %U A224263 647088610,1077366434,1759087854,2820672704,4447425227,6903161705,10558797550,15929753130,23724438995,34906549843 %N A224263 Number of 3 X n 0..2 arrays with rows, diagonals and antidiagonals unimodal and columns nondecreasing. %H A224263 R. H. Hardin, <a href="/A224263/b224263.txt">Table of n, a(n) for n = 1..210</a> %F A224263 Empirical: a(n) = (1/19160064)*n^12 + (1/1064448)*n^11 + (181/6220800)*n^10 + (557/1451520)*n^9 + (13571/2903040)*n^8 + (3197/96768)*n^7 + (8451841/43545600)*n^6 + (316789/483840)*n^5 + (535159/311040)*n^4 + (151169/72576)*n^3 + (9281749/1663200)*n^2 - (73057/13860)*n + 5. %e A224263 Some solutions for n=3: %e A224263 ..0..0..1....0..1..0....1..2..1....0..0..2....0..0..0....1..1..0....0..0..0 %e A224263 ..2..2..1....1..2..0....2..2..2....0..1..2....0..1..0....2..1..0....0..1..0 %e A224263 ..2..2..1....2..2..0....2..2..2....1..2..2....0..1..0....2..2..1....2..1..1 %Y A224263 Row 3 of A224262. %K A224263 nonn %O A224263 1,1 %A A224263 _R. H. Hardin_, Apr 02 2013 %E A224263 Name corrected by _Andrew Howroyd_, Mar 18 2025