A268745 Number of n X 3 binary arrays with some element plus some horizontally or vertically adjacent neighbor totalling two no more than once.

7, 32, 143, 623, 2615, 10830, 44067, 177429, 707163, 2796840, 10986379, 42911627, 166777091, 645395334, 2488065863, 9559464281, 36618142447, 139888931680, 533099140807, 2027067051095, 7692165427919, 29135580083054, 110168752548843

Offset

1,1

Links

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

Formula

Empirical: a(n) = 4*a(n-1) + 8*a(n-2) - 24*a(n-3) - 38*a(n-4) + 4*a(n-5) + 12*a(n-6) - a(n-8).

Empirical g.f.: x*(7 + 4*x - 41*x^2 - 37*x^3 + 13*x^4 + 6*x^5 + x^6 - x^7) / (1 - 2*x - 6*x^2 + x^4)^2. - Colin Barker, Jan 14 2019

Example

Some solutions for n=4:
..1..0..1. .0..0..1. .0..0..0. .1..0..1. .0..0..0. .0..0..1. .0..1..0
..1..0..0. .1..0..0. .0..0..1. .0..0..0. .0..1..0. .1..1..0. .0..0..0
..0..0..0. .0..0..0. .1..0..0. .0..0..0. .0..0..0. .0..0..0. .0..0..0
..0..0..1. .1..1..0. .0..1..1. .0..1..0. .1..1..0. .0..0..1. .0..1..0

Crossrefs

Column 3 of A268750.

Sequence in context: A213163 A249999 A034360 * A199845 A188179 A050148

Adjacent sequences: A268742 A268743 A268744 * A268746 A268747 A268748

Keyword

nonn

Author

R. H. Hardin, Feb 12 2016

Status

approved