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A269895 Number of n X 1 0..6 arrays with some element plus some horizontally or vertically adjacent neighbor totalling six exactly once. 2
0, 7, 84, 756, 6048, 45360, 326592, 2286144, 15676416, 105815808, 705438720, 4655895552, 30474952704, 198087192576, 1279948013568, 8228237230080, 52660718272512, 335712078987264, 2132759090036736, 13507474236899328 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 1 of A269902.

LINKS

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

FORMULA

Empirical: a(n) = 12*a(n-1) - 36*a(n-2).

Conjectures from Colin Barker, Mar 22 2018: (Start)

G.f.: 7*x^2 / (1 - 6*x)^2.

a(n) = 7*6^(n-2)*(n-1).

(End)

EXAMPLE

Some solutions for n=4:

..4. .0. .0. .3. .4. .3. .4. .0. .4. .1. .4. .2. .2. .4. .4. .1

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

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

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

CROSSREFS

Cf. A269902.

Sequence in context: A316377 A053128 A027819 * A272496 A177009 A099674

Adjacent sequences: A269892 A269893 A269894 * A269896 A269897 A269898

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 07 2016

STATUS

approved

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Last modified December 3 20:52 EST 2022. Contains 358543 sequences. (Running on oeis4.)