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 A224184 #8 Jul 23 2025 05:01:48 %S A224184 3,36,684,15779,408222,11444292,340780382,10635858679,344674481333, %T A224184 11518916935288,394956511554556,13839075880034056,494013661434533634, %U A224184 17921279299283914328,659361786079631903704,24563166523294240335463 %N A224184 Number of n X n 0..2 arrays with rows unimodal and columns nondecreasing. %C A224184 Diagonal of A224190 %H A224184 R. H. Hardin, <a href="/A224184/b224184.txt">Table of n, a(n) for n = 1..19</a> %e A224184 Some solutions for n=3 %e A224184 ..0..1..0....0..1..0....2..0..0....0..0..2....0..0..1....1..0..0....0..2..0 %e A224184 ..0..1..0....0..1..1....2..0..0....2..2..2....0..0..1....1..0..0....2..2..1 %e A224184 ..1..2..0....1..1..1....2..1..1....2..2..2....1..1..2....2..0..0....2..2..1 %K A224184 nonn %O A224184 1,1 %A A224184 _R. H. Hardin_ Apr 01 2013