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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. 1
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

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Last modified October 6 04:36 EDT 2022. Contains 357261 sequences. (Running on oeis4.)