A302323 Number of 2Xn 0..1 arrays with every element equal to 0, 1, 2 or 4 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.

2, 8, 20, 52, 136, 360, 960, 2576, 6944, 18784, 50944, 138432, 376704, 1026176, 2797568, 7631104, 20824576, 56845824, 155209728, 423848960, 1157593088, 3161835520, 8636760064, 23592996864, 64451125248, 176071467008, 481011630080

Offset

1,1

Comments

Row 2 of A302322.

Links

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

Formula

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

Example

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

Crossrefs

Cf. A302322.

Sequence in context: A058405 A133326 A285185 * A192698 A305050 A279898

Adjacent sequences: A302320 A302321 A302322 * A302324 A302325 A302326

Keyword

nonn

Author

R. H. Hardin, Apr 05 2018

Status

approved