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 A224264 #7 Mar 18 2025 22:32:38 %S A224264 15,225,2017,12467,59855,240829,850875,2717731,8000608,22004896, %T A224264 57114321,140968221,332855049,755508149,1654943378,3509994992, %U A224264 7227765020,14484196632,28304567857,54032736159,100918573991,184671328897,331497593861,584386115169,1012744010692 %N A224264 Number of 4 X n 0..2 arrays with rows, diagonals and antidiagonals unimodal and columns nondecreasing. %H A224264 R. H. Hardin, <a href="/A224264/b224264.txt">Table of n, a(n) for n = 1..210</a> %F A224264 Empirical: a(n) = (1/106748928000)*n^16 + (1/13343616000)*n^15 + (71/9340531200)*n^14 + (341/3396556800)*n^13 + (70619/28740096000)*n^12 + (6403/186624000)*n^11 + (29921/65318400)*n^10 + (938611/261273600)*n^9 + (179393437/5225472000)*n^8 + (211646789/1306368000)*n^7 + (955811279/1437004800)*n^6 + (152465767/51321600)*n^5 - (11075280679/15567552000)*n^4 - (274011991/117936000)*n^3 + (8155853/123552)*n^2 - (184217/936)*n + 242 for n>2. %e A224264 Some solutions for n=3: %e A224264 ..0..0..2....0..0..0....2..1..0....1..0..0....0..0..1....0..0..0....0..1..1 %e A224264 ..2..2..2....1..0..0....2..1..0....2..0..0....0..0..1....0..1..1....0..1..1 %e A224264 ..2..2..2....1..1..1....2..1..0....2..1..0....0..0..2....1..1..1....1..2..1 %e A224264 ..2..2..2....2..2..2....2..2..1....2..2..1....0..2..2....1..2..1....1..2..1 %Y A224264 Row 4 of A224262. %K A224264 nonn %O A224264 1,1 %A A224264 _R. H. Hardin_, Apr 02 2013 %E A224264 Name corrected by _Andrew Howroyd_, Mar 18 2025