A268990 Number of n X 3 binary arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling two not more than once.

7, 35, 174, 849, 4083, 19416, 91491, 427863, 1988142, 9187653, 42256599, 193542240, 883204143, 4017241083, 18219040206, 82410172617, 371879874987, 1674499435176, 7525052043819, 33755742643791, 151168877259918, 675941817039645

Offset

1,1

Links

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

Formula

Empirical: a(n) = 10*a(n-1) - 31*a(n-2) + 30*a(n-3) - 9*a(n-4).

Empirical g.f.: x*(7 - 35*x + 41*x^2 - 16*x^3) / (1 - 5*x + 3*x^2)^2. - Colin Barker, Jan 17 2019

Example

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

Crossrefs

Column 3 of A268995.

Sequence in context: A110213 A034348 A249793 * A005055 A037506 A037689

Adjacent sequences: A268987 A268988 A268989 * A268991 A268992 A268993

Keyword

nonn

Author

R. H. Hardin, Feb 17 2016

Status

approved