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 A224007 #8 Aug 26 2018 05:46:02 %S A224007 10,100,868,7378,62764,534352,4549684,38737252,329817976,2808146488, %T A224007 23909211472,203568584872,1733230255168,14757125302768, %U A224007 125645595288400,1069775806044208,9108319894356832,77550352914336256,660281732184575104 %N A224007 Number of n X 3 0..2 arrays with rows nondecreasing and antidiagonals unimodal. %C A224007 Column 3 of A224012. %H A224007 R. H. Hardin, <a href="/A224007/b224007.txt">Table of n, a(n) for n = 1..210</a> %F A224007 Empirical: a(n) = 10*a(n-1) - 16*a(n-2) + 30*a(n-3) - 14*a(n-4) + 12*a(n-5). %F A224007 Empirical g.f.: 2*x*(5 + 14*x^2 - x^3 + 6*x^4) / (1 - 10*x + 16*x^2 - 30*x^3 + 14*x^4 - 12*x^5). - _Colin Barker_, Aug 26 2018 %e A224007 Some solutions for n=3: %e A224007 ..1..2..2....0..0..0....0..0..0....0..1..1....0..0..2....1..2..2....1..2..2 %e A224007 ..0..0..0....1..1..2....0..1..2....0..1..2....1..1..2....0..2..2....2..2..2 %e A224007 ..0..1..1....0..0..0....1..1..2....0..0..2....0..0..1....1..1..1....0..1..1 %Y A224007 Cf. A224012. %K A224007 nonn %O A224007 1,1 %A A224007 _R. H. Hardin_, Mar 30 2013