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 A224205 #6 Jul 23 2025 05:03:17 %S A224205 64,1600,16060,108625,586343,2734683,11446096,43787371,154644169, %T A224205 507763502,1559390798,4504599056,12304311893,31936080080,79116405604, %U A224205 187828358540,428877669532,944895859570,2014476071694,4166609485641 %N A224205 Number of 3Xn 0..3 arrays with rows unimodal and antidiagonals nondecreasing. %C A224205 Row 3 of A224204 %H A224205 R. H. Hardin, <a href="/A224205/b224205.txt">Table of n, a(n) for n = 1..210</a> %F A224205 Empirical: a(n) = (1/3629463552000)*n^18 + (1/44808192000)*n^17 + (10403/10461394944000)*n^16 + (10537/373621248000)*n^15 + (2917237/5230697472000)*n^14 + (6087761/747242496000)*n^13 + (5301533/57480192000)*n^12 + (3437329/4105728000)*n^11 + (464094467/73156608000)*n^10 + (442073521/10450944000)*n^9 + (211531872283/804722688000)*n^8 + (20899761511/14370048000)*n^7 + (120074702257/20756736000)*n^6 + (177621646127/13343616000)*n^5 + (1548685310923/72648576000)*n^4 + (22497639401/1297296000)*n^3 + (9654394423/1715313600)*n^2 + (19245361/1021020)*n - 20 %e A224205 Some solutions for n=3 %e A224205 ..0..1..2....2..3..0....0..2..1....2..2..1....0..2..0....1..0..0....3..1..0 %e A224205 ..2..2..0....3..3..0....3..1..0....3..3..2....2..1..0....1..2..1....1..2..3 %e A224205 ..2..2..1....3..3..2....2..3..1....3..2..1....1..2..1....2..3..2....2..3..2 %K A224205 nonn %O A224205 1,1 %A A224205 _R. H. Hardin_ Apr 01 2013