cp's OEIS Frontend

A200528 Number of n X 2 0..2 arrays with every row and column running average nondecreasing rightwards and downwards.

%I A200528 #8 May 21 2018 09:45:23
%S A200528 6,20,57,146,354,825,1873,4169,9144,19825,42590,90815,192457,405760,
%T A200528 851740,1781227,3713015,7718092,16003641,33111477,68374642,140947848,
%U A200528 290098848,596244613,1223916576,2509450811,5139839214,10517282966
%N A200528 Number of n X 2 0..2 arrays with every row and column running average nondecreasing rightwards and downwards.
%C A200528 Column 2 of A200534.
%H A200528 R. H. Hardin, <a href="/A200528/b200528.txt">Table of n, a(n) for n = 1..210</a>
%F A200528 Empirical: a(n) = 7*a(n-1) -16*a(n-2) +6*a(n-3) +27*a(n-4) -33*a(n-5) -3*a(n-6) +24*a(n-7) -11*a(n-8) -4*a(n-9) +4*a(n-10).
%F A200528 Empirical g.f.: x*(6 - 22*x + 13*x^2 + 31*x^3 - 38*x^4 - x^5 + 25*x^6 - 11*x^7 - 4*x^8 + 4*x^9) / ((1 - x)*(1 + x)*(1 - 2*x)^2*(1 - x - x^2)*(1 - 2*x + x^3 - x^4)). - _Colin Barker_, May 21 2018
%e A200528 Some solutions for n=4:
%e A200528 ..0..0....0..1....1..2....0..0....0..0....0..0....0..0....0..0....0..1....0..0
%e A200528 ..1..1....2..2....1..2....0..2....1..1....0..2....0..1....1..1....1..2....0..1
%e A200528 ..1..2....1..2....1..2....0..1....2..2....0..1....2..2....2..2....1..2....0..2
%e A200528 ..1..1....1..2....2..2....1..1....1..1....0..1....1..1....1..2....2..2....0..2
%Y A200528 Cf. A200534.
%K A200528 nonn
%O A200528 1,1
%A A200528 _R. H. Hardin_, Nov 18 2011