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 A224311 #6 Jul 23 2025 05:05:49 %S A224311 27,324,1586,5996,20214,61953,174378,454832,1108958,2547780,5554847, %T A224311 11564081,23107746,44519456,83011127,150287312,264917825,455762696, %U A224311 766835415,1264104630,2044874898,3250558135,5083853932,7831604260 %N A224311 Number of 3Xn 0..2 arrays with diagonals and rows unimodal and antidiagonals nondecreasing. %C A224311 Row 3 of A224310 %H A224311 R. H. Hardin, <a href="/A224311/b224311.txt">Table of n, a(n) for n = 1..210</a> %F A224311 Empirical: a(n) = (1/19160064)*n^12 + (1/1064448)*n^11 + (1507/43545600)*n^10 + (73/161280)*n^9 + (23603/2903040)*n^8 + (111/3584)*n^7 + (13023121/43545600)*n^6 + (130093/96768)*n^5 + (5619469/2177280)*n^4 + (54895/2688)*n^3 - (11456441/1663200)*n^2 + (205131/1540)*n - 196 for n>3 %e A224311 Some solutions for n=3 %e A224311 ..1..2..0....2..1..1....0..0..0....0..2..1....1..0..0....2..2..1....2..0..0 %e A224311 ..2..2..0....2..2..0....0..2..0....2..2..0....0..2..1....2..2..0....0..2..0 %e A224311 ..2..2..2....2..0..0....2..0..0....2..1..1....2..2..1....2..2..0....2..1..1 %K A224311 nonn %O A224311 1,1 %A A224311 _R. H. Hardin_ Apr 03 2013