A218366 - OEIS

%I #4 Oct 27 2012 06:02:55

%S 3,15,63,253,1009,4033,16129,64511,258015,1031935,4127233,16506913,

%T 66019585,264046081,1056055299,4223705151,16892756671,67562771965,

%U 270218073025,1080740248897,4322432887297,17287619374079,69142029827999

%N Hilltop maps: number of nX2 binary arrays indicating the locations of corresponding elements not exceeded by any horizontal, vertical or antidiagonal neighbor in a random 0..3 nX2 array

%C Column 2 of A218372

%H R. H. Hardin, <a href="/A218366/b218366.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 3*a(n-1) +3*a(n-2) +3*a(n-3) +3*a(n-4) +3*a(n-5) +3*a(n-6) +a(n-7) +a(n-8) +a(n-9) +a(n-10) +a(n-11) +a(n-12) +a(n-13)

%e Some solutions for n=3

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

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

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

%K nonn

%O 1,1

%A _R. H. Hardin_ Oct 27 2012