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 A224282 #6 Jul 23 2025 05:04:33 %S A224282 64,1600,13683,84132,442089,2059793,8626382,32788075,114177368, %T A224282 367630559,1103854119,3114501259,8312578140,21108455323,51251494995, %U A224282 119493052710,268514504126,583406544627,1229033304669,2516545359868,5019124209561 %N A224282 Number of 3Xn 0..3 arrays with diagonals and rows unimodal and antidiagonals nondecreasing. %C A224282 Row 3 of A224281 %H A224282 R. H. Hardin, <a href="/A224282/b224282.txt">Table of n, a(n) for n = 1..210</a> %F A224282 Empirical: a(n) = (1/3629463552000)*n^18 + (1/80654745600)*n^17 + (1123/2092278988800)*n^16 + (37607/2615348736000)*n^15 + (1660537/5230697472000)*n^14 + (58097/11496038400)*n^13 + (870097/11496038400)*n^12 + (18766109/28740096000)*n^11 + (404719067/73156608000)*n^10 + (535345591/14631321600)*n^9 + (24473380931/160944537600)*n^8 + (549661909/449064000)*n^7 + (1232106541/768768000)*n^6 + (74468938879/3736212480)*n^5 + (59979142753/8717829120)*n^4 + (521837272841/9081072000)*n^3 + (1774626948209/5145940800)*n^2 - (140683661/117810)*n + 1114 for n>3 %e A224282 Some solutions for n=3 %e A224282 ..0..0..0....2..3..1....0..3..1....1..0..0....0..3..0....0..0..0....0..0..0 %e A224282 ..2..0..0....3..1..0....3..2..1....3..3..2....3..2..1....1..1..2....0..3..2 %e A224282 ..0..0..2....2..2..1....2..1..1....3..2..0....3..3..3....3..2..2....3..3..0 %K A224282 nonn %O A224282 1,1 %A A224282 _R. H. Hardin_ Apr 02 2013