login
A268997
Number of 3 X n binary arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling two not more than once.
1
8, 41, 174, 805, 3331, 14080, 57287, 232449, 928886, 3688159, 14524152, 56872865, 221485093, 858684462, 3315594029, 12757162785, 48929395140, 187135343189, 713890088738, 2717075148077, 10319450344743, 39117842242220
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) + 12*a(n-2) - 16*a(n-3) - 62*a(n-4) - 34*a(n-5) + 16*a(n-6) + 12*a(n-7) - a(n-8) - a(n-9).
Empirical g.f.: x*(8 + 17*x - 45*x^2 - 81*x^3 - 20*x^4 + 25*x^5 + 9*x^6 - 2*x^7 - x^8) / ((1 + x)*(1 - 2*x - 6*x^2 + x^4)^2). - Colin Barker, Jan 18 2019
EXAMPLE
Some solutions for n=4:
..1..0..1..1. .0..0..0..0. .0..1..0..0. .0..0..0..1. .1..0..1..0
..0..0..0..0. .0..0..1..0. .0..1..0..1. .1..0..0..1. .1..0..1..0
..1..0..0..0. .0..1..0..1. .0..1..0..1. .0..1..0..1. .1..0..1..1
CROSSREFS
Row 3 of A268995.
Sequence in context: A133106 A358588 A272843 * A078797 A176177 A368529
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 17 2016
STATUS
approved