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A269215 Number of 2 X n 0..3 arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling three exactly once. 2
0, 96, 768, 6528, 49536, 360960, 2546304, 17563392, 119091072, 796813824, 5274483840, 34608512256, 225420724608, 1459142258688, 9394561013376, 60205610853120, 384263133750144, 2443755614295552, 15491594556534912 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Row 2 of A269214.

LINKS

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

FORMULA

Empirical: a(n) = 10*a(n-1) - 13*a(n-2) - 60*a(n-3) - 36*a(n-4).

G.f.: 96*x^2*(1 - x)^2 / ((1 + x)^2*(1 - 6*x)^2).

a(n) = 8*(175*6^n*n + 1008*n - 55*6^n - 288) / 1029 for n even.

a(n) = 8*(175*6^n*n - 1008*n - 55*6^n + 288) / 1029 for n odd.

(End)

EXAMPLE

Some solutions for n=4:

..3..1..1..0. .3..2..2..2. .0..1..1..1. .2..0..2..0. .3..3..3..3

..3..2..0..1. .2..0..2..0. .3..3..3..1. .1..2..2..2. .0..1..1..1

CROSSREFS

Cf. A269214.

Sequence in context: A232405 A269032 A187610 * A096783 A253410 A326576

Adjacent sequences:  A269212 A269213 A269214 * A269216 A269217 A269218

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 20 2016

STATUS

approved

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Last modified July 16 09:13 EDT 2020. Contains 335784 sequences. (Running on oeis4.)