A318540 Number of nX3 0..1 arrays with every element unequal to 0, 1, 4 or 6 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.

3, 3, 6, 13, 26, 52, 107, 218, 442, 899, 1829, 3720, 7565, 15384, 31288, 63632, 129408, 263180, 535236, 1088521, 2213749, 4502149, 9156120, 18621004, 37869943, 77016935, 156631035, 318543977, 647829886, 1317505875, 2679440650, 5449237333

Offset

1,1

Comments

Column 3 of A318545.

Links

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

Formula

Empirical: a(n) = a(n-1) +3*a(n-3) +a(n-4) +3*a(n-5) +a(n-7) for n>8

Example

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

Crossrefs

Cf. A318545.

Sequence in context: A123140 A123289 A096572 * A325879 A325865 A110523

Adjacent sequences: A318537 A318538 A318539 * A318541 A318542 A318543

Keyword

nonn

Author

R. H. Hardin, Aug 28 2018

Status

approved