cp's OEIS Frontend

A185513 Number of (n+1) X 2 0..2 arrays with every 2 X 2 subblock singular.

%I A185513 #8 Apr 16 2018 08:37:46
%S A185513 31,143,593,2553,10847,46303,197329,841449,3587359,15295151,65211089,
%T A185513 278030937,1185395807,5053987327,21547889233,91870352457,391693178911,
%U A185513 1670000659151,7120119353681,30356933960889,129428088631391
%N A185513 Number of (n+1) X 2 0..2 arrays with every 2 X 2 subblock singular.
%C A185513 Column 1 of A185521.
%H A185513 R. H. Hardin, <a href="/A185513/b185513.txt">Table of n, a(n) for n = 1..200</a>
%F A185513 Empirical: a(n) = 4*a(n-1) + 3*a(n-2) - 8*a(n-3).
%F A185513 Empirical g.f.: x*(31 + 19*x - 72*x^2) / (1 - 4*x - 3*x^2 + 8*x^3). - _Colin Barker_, Apr 16 2018
%e A185513 Some solutions for 3 X 2:
%e A185513 ..0..2....0..0....2..1....0..1....2..0....1..0....1..2....2..0....1..1....1..0
%e A185513 ..0..0....0..1....2..1....0..0....0..0....1..0....0..0....0..0....0..0....2..0
%e A185513 ..1..0....0..2....0..0....1..1....0..2....1..0....0..1....0..0....1..2....2..0
%Y A185513 Cf. A185521.
%K A185513 nonn
%O A185513 1,1
%A A185513 _R. H. Hardin_, Jan 29 2011