A218190 Hilltop maps: number of nX2 binary arrays indicating the locations of corresponding elements not exceeded by any horizontal or vertical neighbor in a random 0..3 nX2 array.

3, 15, 63, 251, 1001, 4001, 16001, 63985, 255867, 1023171, 4091495, 16361227, 65425905, 261627633, 1046206665, 4183611549, 16729587163, 66898918163, 267517973263, 1069761185739, 4277802274577, 17106240667845, 68405094720089

Offset

1,1

Comments

Column 2 of A218196

Links

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

Formula

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

Example

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

Crossrefs

Sequence in context: A383365 A229277 A218313 * A216757 A218366 A359082

Adjacent sequences: A218187 A218188 A218189 * A218191 A218192 A218193

Keyword

nonn

Author

R. H. Hardin, Oct 23 2012

Status

approved