login
A297369
Number of n X 3 0..1 arrays with every 1 horizontally or antidiagonally adjacent to 0, 1 or 2 neighboring 1s.
1
8, 57, 393, 2719, 18805, 130063, 899565, 6221735, 43031893, 297624991, 2058487997, 14237288407, 98470518885, 681059680207, 4710468607821, 32579398179207, 225331548533621, 1558478965304063, 10779035164411613, 74551919956746807
OFFSET
1,1
LINKS
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
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 29 2017
STATUS
approved