A318345 Number of nX3 0..1 arrays with every element unequal to 0, 1, 3 or 6 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.

3, 4, 6, 13, 21, 41, 71, 130, 237, 439, 802, 1483, 2734, 5067, 9351, 17309, 32017, 59290, 109700, 203097, 375959, 696116, 1288668, 2385953, 4417419, 8178970, 15142943, 28037280, 51910866, 96113811, 177954611, 329485125, 610044725, 1129506327

Offset

1,1

Comments

Column 3 of A318350.

Links

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

Formula

Empirical: a(n) = a(n-1) +a(n-3) +6*a(n-4) -2*a(n-5) -2*a(n-7) -11*a(n-8) -3*a(n-9) -3*a(n-11) +6*a(n-12) +4*a(n-13) +4*a(n-15) -a(n-16) -a(n-17) -a(n-19) for n>25

Example

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

Crossrefs

Cf. A318350.

Sequence in context: A226792 A286292 A180647 * A357356 A143100 A369545

Adjacent sequences: A318342 A318343 A318344 * A318346 A318347 A318348

Keyword

nonn

Author

R. H. Hardin, Aug 24 2018

Status

approved