A251243 - OEIS

%I #8 Nov 27 2018 09:01:37

%S 621,14265,327753,7530633,173028393,3975606801,91345992921,

%T 2098821870081,48223825786089,1108020364732593,25458559305394041,

%U 584951560945849089,13440207851070791625,308810505245808515409,7095420636859874120985

%N Number of (n+1) X (2+1) 0..2 arrays with no 2 X 2 subblock having the sum of its diagonal elements less than the minimum of its antidiagonal elements.

%H R. H. Hardin, <a href="/A251243/b251243.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 27*a(n-1) - 94*a(n-2) + 36*a(n-3) - 4*a(n-4) - 36*a(n-5).

%F Empirical g.f.: 9*x*(69 - 278*x + 108*x^2 - 16*x^3 - 108*x^4) / (1 - 27*x + 94*x^2 - 36*x^3 + 4*x^4 + 36*x^5). - _Colin Barker_, Nov 27 2018

%e Some solutions for n=2:

%e ..1..1..2....1..0..2....2..0..0....2..2..2....2..2..0....0..1..0....1..0..0

%e ..0..1..1....2..0..2....0..1..0....1..1..0....1..1..1....2..2..2....0..0..0

%e ..2..2..0....2..0..1....2..2..2....2..1..2....1..1..2....1..0..1....0..2..2

%Y Column 2 of A251249.

%K nonn

%O 1,1

%A _R. H. Hardin_, Dec 01 2014