%I #8 Aug 26 2018 05:46:05
%S 15,225,2661,28541,297859,3094127,32148473,334179881,3474343713,
%T 36122604265,375565139165,3904724751131,40597113853797,
%U 422084894246843,4388382334042279,45625654988950821,474366234758987515
%N Number of n X 4 0..2 arrays with rows nondecreasing and antidiagonals unimodal.
%C Column 4 of A224012.
%H R. H. Hardin, <a href="/A224008/b224008.txt">Table of n, a(n) for n = 1..210</a>
%F 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 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 Some solutions for n=3:
%e ..0..0..2..2....0..1..1..2....1..1..1..2....1..2..2..2....0..0..0..1
%e ..0..0..2..2....1..2..2..2....0..1..1..1....0..0..0..0....0..2..2..2
%e ..0..0..0..2....2..2..2..2....0..1..2..2....0..0..1..1....0..1..1..1
%Y Cf. A224012.
%K nonn
%O 1,1
%A _R. H. Hardin_, Mar 30 2013
|