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 A224191 #6 Jul 23 2025 05:02:06 %S A224191 15,225,2205,15779,89380,422488,1727738,6272940,20614382,62231446, %T A224191 174603882,459586532,1143581612,2707062766,6128575771,13328965295, %U A224191 27955737041,56730240471,111704250407,213954477597,399506181220 %N A224191 Number of 4Xn 0..2 arrays with rows unimodal and columns nondecreasing. %C A224191 Row 4 of A224190 %H A224191 R. H. Hardin, <a href="/A224191/b224191.txt">Table of n, a(n) for n = 1..210</a> %F A224191 Empirical: a(n) = (1/106748928000)*n^16 + (1/1482624000)*n^15 + (7/266872320)*n^14 + (127/197683200)*n^13 + (311999/28740096000)*n^12 + (212351/1596672000)*n^11 + (31937/26127360)*n^10 + (83129/9676800)*n^9 + (34840531/746496000)*n^8 + (9481183/48384000)*n^7 + (90994151/143700480)*n^6 + (123257231/79833600)*n^5 + (43399375531/15567552000)*n^4 + (2360326763/648648000)*n^3 + (218135/61776)*n^2 + (581099/360360)*n + 1 %e A224191 Some solutions for n=3 %e A224191 ..0..0..0....0..0..1....0..1..0....0..1..0....0..0..0....1..0..0....0..0..0 %e A224191 ..0..0..1....0..0..1....0..2..0....0..2..0....0..0..0....1..0..0....1..0..0 %e A224191 ..0..0..2....1..2..2....0..2..1....2..2..1....0..1..1....2..1..0....1..1..2 %e A224191 ..0..1..2....1..2..2....0..2..2....2..2..2....0..2..2....2..1..0....2..2..2 %K A224191 nonn %O A224191 1,1 %A A224191 _R. H. Hardin_ Apr 01 2013