A317890 Number of nX2 0..1 arrays with every element unequal to 2, 3 or 4 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.

0, 1, 1, 2, 5, 16, 45, 123, 340, 946, 2629, 7298, 20260, 56254, 156197, 433691, 1204165, 3343437, 9283266, 25775569, 71567464, 198711505, 551734847, 1531926100, 4253488018, 11810073809, 32791403882, 91047370756, 252798683166

Offset

1,4

Comments

Column 2 of A317896.

Links

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

Formula

Empirical: a(n) = 2*a(n-1) +a(n-2) +2*a(n-3) +3*a(n-4) +a(n-5) for n>6

Example

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

Crossrefs

Cf. A317896.

Sequence in context: A148374 A182884 A152428 * A138573 A148375 A075887

Adjacent sequences: A317887 A317888 A317889 * A317891 A317892 A317893

Keyword

nonn

Author

R. H. Hardin, Aug 10 2018

Status

approved