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A269896 Number of n X 2 0..6 arrays with some element plus some horizontally or vertically adjacent neighbor totalling six exactly once. 1
7, 840, 45360, 2005080, 80724000, 3078006120, 113260615440, 4064194275960, 143136593671680, 4968778108446600, 170509976205204720, 5796622762505510040, 195530524142139886560, 6552338022044877818280, 218340123666185993749200 (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) = 62*a(n-1) - 961*a(n-2) for n>3.

Conjectures from Colin Barker, Jan 29 2019: (Start)

G.f.: 7*x*(1 + 58*x + x^2) / (1 - 31*x)^2.

a(n) = 840 * 31^(n-3) * (23*n-15) for n>1.

(End)

EXAMPLE

Some solutions for n=3:

..2..1. .1..5. .2..2. .2..4. .4..2. .3..5. .4..2. .3..6. .0..0. .4..3

..5..6. .4..6. .4..6. .6..1. .6..6. .3..4. .3..5. .4..2. .2..5. .5..1

..1..1. .1..6. .1..1. .6..3. .3..2. .6..3. .4..5. .1..6. .0..1. .4..3

CROSSREFS

Column 2 of A269902.

Sequence in context: A047788 A251698 A203694 * A087350 A308296 A193342

Adjacent sequences: A269893 A269894 A269895 * A269897 A269898 A269899

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 07 2016

STATUS

approved

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Last modified February 1 16:51 EST 2023. Contains 359993 sequences. (Running on oeis4.)