cp's OEIS Frontend

A221447 Hilltop maps: number of 2 X n binary arrays indicating the locations of corresponding elements not exceeded by any horizontal or antidiagonal neighbor in a random 0..1 2 X n array.

%I A221447 #7 Aug 05 2018 08:23:03
%S A221447 1,9,33,117,429,1577,5785,21217,77825,285473,1047145,3841029,14089277,
%T A221447 51680881,189570641,695364065,2550664929,9356094041,34319088593,
%U A221447 125885849013,461761883309,1693788766169,6212986580521,22789856102913
%N A221447 Hilltop maps: number of 2 X n binary arrays indicating the locations of corresponding elements not exceeded by any horizontal or antidiagonal neighbor in a random 0..1 2 X n array.
%C A221447 Row 2 of A221446.
%H A221447 R. H. Hardin, <a href="/A221447/b221447.txt">Table of n, a(n) for n = 1..210</a>
%F A221447 Empirical: a(n) = 3*a(n-1) + a(n-2) + 5*a(n-3) + a(n-4) + a(n-5) - a(n-6) - a(n-7).
%F A221447 Empirical g.f.: x*(1 + 6*x + 5*x^2 + 4*x^3 - x^4 - 2*x^5 - x^6) / ((1 + x^2)*(1 - 3*x - 2*x^2 - 2*x^3 + x^4 + x^5)). - _Colin Barker_, Aug 05 2018
%e A221447 Some solutions for n=3:
%e A221447 ..1..0..1....0..1..0....0..1..1....1..0..1....1..1..0....0..1..0....1..1..0
%e A221447 ..0..1..0....1..1..0....0..0..1....1..1..1....1..1..0....0..0..1....0..0..1
%Y A221447 Cf. A221446.
%K A221447 nonn
%O A221447 1,2
%A A221447 _R. H. Hardin_, Jan 17 2013