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 A224045 #6 Jul 23 2025 04:56:57 %S A224045 50,984,9731,67585,376734,1801402,7655477,29502561,104437965, %T A224045 342818189,1051490221,3033475639,8279003183,21484969347,53256520053, %U A224045 126598758740,289630093258,639706047860,1367894672765,2838837855851,5730717831654 %N A224045 Number of nX3 0..3 arrays with rows and columns unimodal and antidiagonals nondecreasing. %C A224045 Column 3 of A224050 %H A224045 R. H. Hardin, <a href="/A224045/b224045.txt">Table of n, a(n) for n = 1..210</a> %F A224045 Empirical: a(n) = (1/3629463552000)*n^18 + (7/403273728000)*n^17 + (667/951035904000)*n^16 + (3253/174356582400)*n^15 + (1895917/5230697472000)*n^14 + (1319281/249080832000)*n^13 + (509321/8211456000)*n^12 + (100859/174182400)*n^11 + (332201027/73156608000)*n^10 + (728354747/24385536000)*n^9 + (143150448337/804722688000)*n^8 + (121759327/136857600)*n^7 + (2559704983/808704000)*n^6 + (221471493559/31135104000)*n^5 + (346834471679/24216192000)*n^4 + (1741800289/181621440)*n^3 + (25437920323/1715313600)*n^2 + (1383692/69615)*n - 32 for n>1 %e A224045 Some solutions for n=3 %e A224045 ..2..0..0....1..1..0....0..1..0....3..3..0....0..0..2....0..1..0....0..0..0 %e A224045 ..3..1..0....1..1..3....3..3..0....3..1..1....0..2..0....1..2..2....0..1..0 %e A224045 ..1..3..0....1..3..1....3..0..0....2..1..1....2..3..0....2..2..2....2..2..3 %K A224045 nonn %O A224045 1,1 %A A224045 _R. H. Hardin_ Apr 01 2013