A218350 Hilltop maps: number of nX4 binary arrays indicating the locations of corresponding elements not exceeded by any horizontal or vertical neighbor in a random 0..1 nX4 array.

9, 149, 2069, 28661, 401253, 5609569, 78394141, 1095695529, 15314367301, 214044940145, 2991651891557, 41813576818545, 584417958076589, 8168264238929833, 114165795446827469, 1595666897305379897

Offset: 1

Author

R. H. Hardin Oct 26 2012

Keywords

• nonn

Comments

Column 4 of A218354

Examples

			Some solutions for n=3
..1..0..0..1....0..1..1..1....1..0..0..1....1..1..0..1....1..1..1..0
..0..0..1..1....0..1..0..1....1..1..1..1....1..1..1..1....0..0..1..1
..0..1..1..1....1..1..1..0....0..1..0..0....0..1..1..1....0..1..0..1
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 10*a(n-1) +36*a(n-2) +242*a(n-3) +413*a(n-4) +482*a(n-5) -720*a(n-6) -2212*a(n-7) -683*a(n-8) +466*a(n-9) +121*a(n-10) -414*a(n-11) -119*a(n-12) -100*a(n-13) +241*a(n-14) +36*a(n-15) +164*a(n-16) -44*a(n-17) +35*a(n-18) -4*a(n-19) +2*a(n-20) +2*a(n-21) -a(n-22)