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A198280 Number of 2n X 6 0..2 arrays with values 0..2 introduced in row major order and each element equal to exactly two horizontal and vertical neighbors. 1
2, 14, 100, 662, 4588, 31718, 219060, 1516006, 10490668, 72598710, 502455316, 3477498838, 24068002412, 166577135174, 1152898456372, 7979341139206, 55225944246124, 382225190106390, 2645425190166548, 18309297185224566 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A198285.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..200

FORMULA

Empirical: a(n) = 8*a(n-1) -2*a(n-2) -20*a(n-3) -145*a(n-4) +68*a(n-5) +492*a(n-6) +512*a(n-7) +64*a(n-8) -2048*a(n-9).

Empirical g.f.: 2*x*(1 - x - 4*x^2 - 35*x^3 + 31*x^4 + 116*x^5 + 148*x^6 - 576*x^8) / (1 - 8*x + 2*x^2 + 20*x^3 + 145*x^4 - 68*x^5 - 492*x^6 - 512*x^7 - 64*x^8 + 2048*x^9). - Colin Barker, May 14 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

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

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

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

CROSSREFS

Cf. A198285.

Sequence in context: A037516 A037719 A158811 * A074620 A185010 A144277

Adjacent sequences:  A198277 A198278 A198279 * A198281 A198282 A198283

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 23 2011

STATUS

approved

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Last modified July 18 07:05 EDT 2019. Contains 325134 sequences. (Running on oeis4.)