A301786 Number of nX4 0..1 arrays with every element equal to 0 or 1 horizontally or antidiagonally adjacent elements, with upper left element zero.

5, 9, 17, 32, 61, 116, 221, 421, 802, 1528, 2911, 5546, 10566, 20130, 38351, 73065, 139201, 265201, 505252, 962589, 1833892, 3493869, 6656401, 12681550, 24160460, 46029691, 87694210, 167072042, 318300002, 606414395, 1155320189, 2201076937

Offset

1,1

Comments

Column 4 of A301790.

Links

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

Formula

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

Example

Some solutions for n=5
..0..0..1..0. .0..1..0..1. .0..1..0..1. .0..1..1..0. .0..0..1..0
..1..0..1..0. .1..0..1..0. .0..1..0..1. .0..0..1..0. .1..0..1..1
..1..0..1..0. .1..0..1..1. .0..1..0..1. .1..0..1..0. .1..0..0..1
..1..0..1..0. .1..0..0..1. .0..1..0..1. .0..1..0..1. .1..1..0..0
..1..0..1..1. .1..1..0..1. .0..1..0..0. .0..1..0..1. .0..1..1..0

Crossrefs

Cf. A301790.

Sequence in context: A180565 A233187 A160426 * A258411 A059743 A000322

Adjacent sequences: A301783 A301784 A301785 * A301787 A301788 A301789

Keyword

nonn

Author

R. H. Hardin, Mar 26 2018

Status

approved