A268997 Number of 3 X n binary arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling two not more than once.

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

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

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

Adjacent sequences: A268994 A268995 A268996 * A268998 A268999 A269000

Keyword

nonn

Author

R. H. Hardin, Feb 17 2016

Status

approved