A269047 - OEIS

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A269047

Number of n X 3 0..2 arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling two not more than once.

24, 102, 594, 3258, 17346, 90450, 464250, 2353338, 11809746, 58773858, 290465706, 1426996746, 6974700162, 33938314674, 164494914138, 794524032090, 3825755303730, 18370501130754, 87990608484618, 420498562000554

(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(n-1) - 29*a(n-2) + 20*a(n-3) - 4*a(n-4) for n>5.

Empirical g.f.: 6*x*(1 - x)*(1 - 2*x)*(4 - 11*x + 4*x^2) / (1 - 5*x + 2*x^2)^2. - Colin Barker, Jan 18 2019

EXAMPLE

Some solutions for n=4:

..2..1..2. .1..2..0. .1..2..2. .1..2..2. .2..1..0. .0..0..0. .0..0..0

..2..1..2. .1..0..1. .1..0..1. .1..2..2. .0..1..2. .0..1..0. .0..0..0

..2..1..0. .0..0..0. .0..0..1. .1..2..1. .2..1..2. .0..1..2. .1..0..1

..2..2..2. .0..0..0. .1..0..0. .0..0..1. .2..2..0. .2..1..2. .1..2..2

CROSSREFS

Column 3 of A269052.

Sequence in context: A048529 A213842 A333033 * A182675 A100155 A304415

Adjacent sequences: A269044 A269045 A269046 * A269048 A269049 A269050

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 18 2016

STATUS

approved