

A279651


Number of n X 2 0..2 arrays with no element equal to a strict majority of its horizontal and antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.


1



1, 3, 24, 232, 2232, 20880, 190656, 1707264, 15046272, 130854656, 1125285888, 9583835136, 80941029376, 678574706688, 5651894845440, 46802046418944, 385539453517824, 3161014415327232, 25806384396763136, 209862489033670656
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OFFSET

1,2


LINKS

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


FORMULA

Empirical: a(n) = 24*a(n1)  204*a(n2) + 704*a(n3)  816*a(n4) + 384*a(n5)  64*a(n6) for n>7.
Empirical g.f.: x*(1  21*x + 156*x^2  436*x^3 + 264*x^4  192*x^5 + 32*x^6) / (1  8*x + 4*x^2)^3.  Colin Barker, Feb 11 2019


EXAMPLE

Some solutions for n=4:
..0..0. .0..0. .0..0. .0..1. .0..1. .0..1. .0..1. .0..1. .0..0. .0..0
..0..1. .0..1. .1..2. .1..1. .1..0. .2..2. .1..2. .1..0. .0..1. .1..1
..2..1. .0..1. .1..1. .1..0. .0..0. .2..2. .2..2. .0..0. .0..2. .1..2
..0..1. .2..0. .1..2. .1..2. .2..2. .1..2. .2..0. .1..1. .2..0. .0..2


CROSSREFS

Column 2 of A279657.
Sequence in context: A307514 A225107 A249926 * A001099 A277462 A230325
Adjacent sequences: A279648 A279649 A279650 * A279652 A279653 A279654


KEYWORD

nonn


AUTHOR

R. H. Hardin, Dec 16 2016


STATUS

approved



