A301995 Number of nX4 0..1 arrays with every element equal to 1, 2 or 4 horizontally or antidiagonally adjacent elements, with upper left element zero.

2, 8, 26, 74, 200, 530, 1394, 3656, 9578, 25082, 65672, 171938, 450146, 1178504, 3085370, 8077610, 21147464, 55364786, 144946898, 379475912, 993480842, 2600966618, 6809419016, 17827290434, 46672452290, 122190066440, 319897747034

Offset

1,1

Comments

Column 4 of A301999.

Links

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

Formula

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

Example

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

Crossrefs

Cf. A301999.

Sequence in context: A136594 A268502 A167826 * A325926 A097040 A302237

Adjacent sequences: A301992 A301993 A301994 * A301996 A301997 A301998

Keyword

nonn

Author

R. H. Hardin, Mar 30 2018

Status

approved