A218237 - OEIS

%I #10 Mar 10 2018 05:46:44

%S 7,63,511,4095,32753,262017,2096129,16769025,134152151,1073216767,

%T 8585730559,68685815807,549486297185,4395888543361,35167093673985,

%U 281336632008705,2250692117004583,18005529423519295,144044175288040447

%N Hilltop maps: number of n X 3 binary arrays indicating the locations of corresponding elements not exceeded by any king-move neighbor in a random 0..3 n X 3 array.

%C Column 3 of A218242.

%H R. H. Hardin, <a href="/A218237/b218237.txt">Table of n, a(n) for n = 1..146</a>

%F Empirical: a(n) = 7*a(n-1) + 7*a(n-2) + 7*a(n-3) + 7*a(n-4) + 7*a(n-5) + 7*a(n-6) + 7*a(n-7).

%F Empirical g.f.: 7*x*(1 + x)^2*(1 + x^2)^2 / (1 - 7*x - 7*x^2 - 7*x^3 - 7*x^4 - 7*x^5 - 7*x^6 - 7*x^7). - _Colin Barker_, Mar 10 2018

%e Some solutions for n=3:

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

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

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

%Y Cf. A218242.

%K nonn

%O 1,1

%A _R. H. Hardin_, Oct 24 2012