A297369 Number of n X 3 0..1 arrays with every 1 horizontally or antidiagonally adjacent to 0, 1 or 2 neighboring 1s.

8, 57, 393, 2719, 18805, 130063, 899565, 6221735, 43031893, 297624991, 2058487997, 14237288407, 98470518885, 681059680207, 4710468607821, 32579398179207, 225331548533621, 1558478965304063, 10779035164411613, 74551919956746807

Offset

1,1

Links

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

Formula

Empirical: a(n) = 7*a(n-1) - 4*a(n-3).

Empirical g.f.: x*(8 + x - 6*x^2) / (1 - 7*x + 4*x^3). - Colin Barker, Feb 27 2019

Example

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

Crossrefs

Column 3 of A297374.

Sequence in context: A108666 A295711 A164031 * A023000 A331792 A097114

Adjacent sequences: A297366 A297367 A297368 * A297370 A297371 A297372

Keyword

nonn

Author

R. H. Hardin, Dec 29 2017

Status

approved