%I #4 Oct 27 2012 06:04:27

%S 15,253,4081,65409,1046529,16744435,267910753,4286570153,68585092161,

%T 1097360991969,17557768153359,280924166963785,4494784695580905,

%U 71916523515869329,1150663870439327625,18410613833999482211

%N Hilltop maps: number of nX4 binary arrays indicating the locations of corresponding elements not exceeded by any horizontal, vertical or antidiagonal neighbor in a random 0..3 nX4 array

%C Column 4 of A218372

%H R. H. Hardin, <a href="/A218368/b218368.txt">Table of n, a(n) for n = 1..119</a>

%F Empirical: a(n) = 15*a(n-1) +15*a(n-2) +15*a(n-3) +15*a(n-4) +13*a(n-5) +33*a(n-6) +107*a(n-7) +107*a(n-8) +107*a(n-9) +106*a(n-10) +110*a(n-11) +142*a(n-12) +232*a(n-13) +175*a(n-14) +175*a(n-15) +175*a(n-16) +169*a(n-17) +161*a(n-18) +115*a(n-19) -53*a(n-20) -53*a(n-21) -53*a(n-22) -51*a(n-23) -16*a(n-24) +56*a(n-25) -85*a(n-26) -43*a(n-27) -43*a(n-28) -43*a(n-29) -39*a(n-30) +19*a(n-31) -5*a(n-32) -7*a(n-33) -7*a(n-34) -7*a(n-35) -8*a(n-36) +2*a(n-37) -6*a(n-38) -2*a(n-39) -3*a(n-40) -3*a(n-41) -3*a(n-42) -a(n-43) -a(n-44) +a(n-45) +a(n-46) +a(n-47) +a(n-48) +a(n-49)

%e Some solutions for n=3

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

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

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

%K nonn

%O 1,1

%A _R. H. Hardin_ Oct 27 2012