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 A223571 #8 Jul 23 2025 04:14:26
%S A223571 27,729,16038,352836,7762392,170772624,3756997728,82653950016,
%T A223571 1818386900352,40004511807744,880099259770368,19362183714948096,
%U A223571 425968041728858112,9371296918034878464,206168532196767326208
%N A223571 Number of nX3 0..2 arrays with antidiagonals unimodal.
%C A223571 Column 3 of A223576
%H A223571 R. H. Hardin, <a href="/A223571/b223571.txt">Table of n, a(n) for n = 1..210</a>
%F A223571 Let U(z) = (z^4+6*z^3+23*z^2+18*z+24)/24
%F A223571 a(n) = U(min(n,3))^(max(n,3)-min(n,3)+1) * product{ U(i)^2 , i=1..(min(n,3)-1) }
%F A223571 a(n) = 22*a(n-1) for n>2
%e A223571 Some solutions for n=3
%e A223571 ..1..2..1....1..2..2....0..1..0....0..1..0....0..2..0....2..0..0....2..1..0
%e A223571 ..2..1..1....0..2..2....0..1..2....1..1..2....1..0..2....1..1..1....2..0..2
%e A223571 ..2..0..0....2..1..0....1..2..1....2..2..1....1..0..0....1..1..0....1..2..2
%K A223571 nonn
%O A223571 1,1
%A A223571 _R. H. Hardin_ Mar 22 2013