cp's OEIS Frontend

A203176 Number of n X 3 0..2 arrays with every 1 immediately preceded by 0 to the left or above, no 0 immediately preceded by a 0, and every 2 immediately preceded by 0 1 to the left or above.

%I A203176 #11 Jun 14 2014 17:24:20
%S A203176 2,2,7,17,41,97,235,607,1415,3486,8648,20838,51170,124939,305270,
%T A203176 746199,1820662,4454559,10877169,26569604,64944236,158629072,
%U A203176 387600053,946993492,2313654220,5653010591,13810992779,33744134975,82444452049
%N A203176 Number of n X 3 0..2 arrays with every 1 immediately preceded by 0 to the left or above, no 0 immediately preceded by a 0, and every 2 immediately preceded by 0 1 to the left or above.
%C A203176 Column 3 of A203181.
%H A203176 R. H. Hardin, <a href="/A203176/b203176.txt">Table of n, a(n) for n = 1..210</a>
%F A203176 Empirical: a(n) = 2*a(n-2) +10*a(n-3) +5*a(n-4) -a(n-5) -31*a(n-6) -7*a(n-7) +30*a(n-9) for n>10.
%F A203176 Empirical G.f.:
%F A203176   2*x -x^2*(2+7*x+13*x^2+7*x^3-17*x^4-50*x^5-13*x^6+18*x^7+54*x^8) / ( -1+2*x^2+10*x^3+5*x^4-x^5-31*x^6-7*x^7+30*x^9 ). - _R. J. Mathar_, Jul 02 2013
%e A203176 Some solutions for n=5:
%e A203176 ..0..1..2....0..1..2....0..1..0....0..1..2....0..1..2....0..1..2....0..1..0
%e A203176 ..1..0..1....1..0..1....1..0..1....1..0..1....1..0..1....1..0..1....1..0..1
%e A203176 ..2..1..0....0..1..2....0..1..0....2..1..0....0..1..0....0..1..2....2..1..2
%e A203176 ..0..1..1....1..0..1....1..0..1....0..2..1....1..2..1....1..0..1....0..1..0
%e A203176 ..1..0..2....0..1..0....0..1..0....1..0..2....2..0..1....0..1..2....1..0..1
%K A203176 nonn
%O A203176 1,1
%A A203176 _R. H. Hardin_, Dec 30 2011