

A268881


Number of n X 3 binary arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling two exactly once.


1



2, 14, 84, 462, 2418, 12252, 60666, 295230, 1417452, 6732102, 31690914, 148080468, 687592338, 3175567374, 14597507076, 66827528094, 304831251762, 1386004252620, 6283722000714, 28414577975934, 128187044049948, 577056144993366
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,1


LINKS

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


FORMULA

Empirical: a(n) = 10*a(n1)  31*a(n2) + 30*a(n3)  9*a(n4).
Empirical g.f.: 2*x*(1  2*x)*(1  x + x^2) / (1  5*x + 3*x^2)^2.  Colin Barker, Jan 15 2019


EXAMPLE

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


CROSSREFS

Column 3 of A268886.
Sequence in context: A077444 A335693 A138126 * A053141 A339281 A036692
Adjacent sequences: A268878 A268879 A268880 * A268882 A268883 A268884


KEYWORD

nonn


AUTHOR

R. H. Hardin, Feb 15 2016


STATUS

approved



