A218367 Hilltop maps: number of nX3 binary arrays indicating the locations of corresponding elements not exceeded by any horizontal, vertical or antidiagonal neighbor in a random 0..3 nX3 array

7, 63, 509, 4081, 32641, 261121, 2088955, 16711551, 133691649, 1069527065, 8556167553, 68448948737, 547588456455, 4380682584267, 35045260136261, 280360476796249, 2242870980092649, 17942865167110001, 143542099952530683

Offset

1,1

Comments

Column 3 of A218372

Links

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

Formula

Empirical: a(n) = 7*a(n-1) +7*a(n-2) +7*a(n-3) +7*a(n-4) +7*a(n-5) +5*a(n-6) +9*a(n-7) +9*a(n-8) +9*a(n-9) +9*a(n-10) +9*a(n-11) +8*a(n-12) +4*a(n-13) +a(n-14) +a(n-15) +a(n-16) +a(n-17) +a(n-18) +a(n-19) -a(n-20) -a(n-21) -a(n-22) -a(n-23) -a(n-24) -a(n-25)

Example

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

Crossrefs

Sequence in context: A182603 A320073 A218191 * A218314 A218633 A218283

Adjacent sequences: A218364 A218365 A218366 * A218368 A218369 A218370

Keyword

nonn

Author

R. H. Hardin Oct 27 2012

Status

approved