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 A224375 #6 Jul 23 2025 05:07:55 %S A224375 27,324,1838,7608,26314,80819,227112,593400,1455898,3378085,7455007, %T A224375 15725041,31840088,62123439,117194882,214407666,381424761,661365902, %U A224375 1120086056,1856304530,3015496746,4808693047,7537606592,11627841824 %N A224375 Number of 3Xn 0..2 arrays with rows unimodal and antidiagonals nondecreasing. %C A224375 Row 3 of A224374 %H A224375 R. H. Hardin, <a href="/A224375/b224375.txt">Table of n, a(n) for n = 1..210</a> %F A224375 Empirical: a(n) = (1/19160064)*n^12 + (1/456192)*n^11 + (2287/43545600)*n^10 + (215/290304)*n^9 + (20603/2903040)*n^8 + (923/17920)*n^7 + (14627101/43545600)*n^6 + (400091/207360)*n^5 + (16965289/2177280)*n^4 + (3069023/362880)*n^3 + (13912639/1663200)*n^2 + (21001/3465)*n - 6 %e A224375 Some solutions for n=3 %e A224375 ..1..0..0....0..0..0....0..2..2....0..2..1....0..0..0....2..0..0....1..2..0 %e A224375 ..0..1..0....2..1..0....2..2..0....2..1..0....0..0..1....1..0..0....2..2..1 %e A224375 ..2..2..0....2..1..1....2..2..2....1..1..0....0..1..2....0..1..1....2..2..1 %K A224375 nonn %O A224375 1,1 %A A224375 _R. H. Hardin_ Apr 05 2013