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 A223720 #6 Jan 20 2024 16:38:52 %S A223720 22,484,5883,46613,273562,1285547,5087912,17557701,54161878,152154419, %T A223720 394849354,957192985,2187192034,4745347460,9834757897,19568773673, %U A223720 37541913638,69694254022,125590862829,220277446621,376922731034 %N A223720 Number of n X 3 0..2 arrays with rows, antidiagonals and columns unimodal. %C A223720 Column 3 of A223725. %H A223720 R. H. Hardin, <a href="/A223720/b223720.txt">Table of n, a(n) for n = 1..210</a> %F A223720 Empirical: a(n) = (5051/239500800)*n^12 + (61/177408)*n^11 + (91271/21772800)*n^10 + (27/896)*n^9 + (1198121/7257600)*n^8 + (1087/1792)*n^7 + (36617153/21772800)*n^6 + (63719/20160)*n^5 + (26821099/5443200)*n^4 + (305/56)*n^3 + (149993/207900)*n^2 + (3277/770)*n + 1. %e A223720 Some solutions for n=3 %e A223720 ..0..0..1....2..2..0....2..2..1....0..2..1....2..2..1....0..1..0....2..2..1 %e A223720 ..0..0..2....1..1..1....2..1..0....1..2..1....1..1..1....2..1..1....0..1..1 %e A223720 ..0..1..0....0..1..2....2..1..0....2..2..2....1..1..2....0..2..2....0..0..0 %Y A223720 Cf. A223725. %K A223720 nonn %O A223720 1,1 %A A223720 _R. H. Hardin_, Mar 26 2013