A218837 Unmatched value maps: number of n X 3 binary arrays indicating the locations of corresponding elements not equal to any horizontal or antidiagonal neighbor in a random 0..1 n X 3 array.

4, 20, 93, 436, 2043, 9573, 44857, 210190, 984904, 4615043, 21625074, 101330329, 474811581, 2224862385, 10425214612, 48850257184, 228901534957, 1072582125992, 5025883366023, 23550181377025, 110350957732161, 517080258425742

Offset

1,1

Comments

Column 3 of A218842.

Links

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

Formula

Empirical: a(n) = 4*a(n-1) + 3*a(n-2) + a(n-3).

Empirical g.f.: x*(2 + x)^2 / (1 - 4*x - 3*x^2 - x^3). - Colin Barker, Mar 10 2018

Example

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

Crossrefs

Cf. A218842.

Sequence in context: A166175 A094971 A239650 * A254943 A099025 A008353

Adjacent sequences: A218834 A218835 A218836 * A218838 A218839 A218840

Keyword

nonn

Author

R. H. Hardin, Nov 07 2012

Status

approved