A318062 Number of nX2 0..1 arrays with every element unequal to 1, 2, 3 or 4 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.

1, 5, 18, 67, 249, 925, 3437, 12770, 47447, 176289, 655001, 2433653, 9042226, 33596347, 124827065, 463794357, 1723225693, 6402636738, 23788965871, 88387787777, 328404398513, 1220184956261, 4533591310674, 16844536614515

Offset

1,2

Comments

Column 2 of A318068.

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) -a(n-3) -a(n-4)

Example

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

Crossrefs

Cf. A318068.

Sequence in context: A225015 A371871 A166677 * A158879 A322497 A279488

Adjacent sequences: A318059 A318060 A318061 * A318063 A318064 A318065

Keyword

nonn

Author

R. H. Hardin, Aug 15 2018

Status

approved