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 A224008 #8 Aug 26 2018 05:46:05 %S A224008 15,225,2661,28541,297859,3094127,32148473,334179881,3474343713, %T A224008 36122604265,375565139165,3904724751131,40597113853797, %U A224008 422084894246843,4388382334042279,45625654988950821,474366234758987515 %N A224008 Number of n X 4 0..2 arrays with rows nondecreasing and antidiagonals unimodal. %C A224008 Column 4 of A224012. %H A224008 R. H. Hardin, <a href="/A224008/b224008.txt">Table of n, a(n) for n = 1..210</a> %F A224008 Empirical: a(n) = 15*a(n-1) - 58*a(n-2) + 105*a(n-3) + 20*a(n-4) - 183*a(n-5) + 220*a(n-6) + 240*a(n-7). %F A224008 Empirical g.f.: x*(15 + 156*x^2 + 101*x^3 + 157*x^4 + 460*x^5 + 240*x^6) / (1 - 15*x + 58*x^2 - 105*x^3 - 20*x^4 + 183*x^5 - 220*x^6 - 240*x^7). - _Colin Barker_, Aug 26 2018 %e A224008 Some solutions for n=3: %e A224008 ..0..0..2..2....0..1..1..2....1..1..1..2....1..2..2..2....0..0..0..1 %e A224008 ..0..0..2..2....1..2..2..2....0..1..1..1....0..0..0..0....0..2..2..2 %e A224008 ..0..0..0..2....2..2..2..2....0..1..2..2....0..0..1..1....0..1..1..1 %Y A224008 Cf. A224012. %K A224008 nonn %O A224008 1,1 %A A224008 _R. H. Hardin_, Mar 30 2013