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A223381 Number of n X 2 0..2 arrays with all horizontally or vertically connected equal values in a straight line, and new values 0..2 introduced in row major order. 1
2, 9, 57, 366, 2358, 15204, 98052, 632376, 4078488, 26304144, 169648272, 1094144736, 7056675168, 45511953984, 293528880192, 1893111501696, 12209603211648, 78745710676224, 507869653293312, 3275500119584256 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A223387.

LINKS

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

FORMULA

Empirical: a(n) = 8*a(n-1) - 10*a(n-2) for n>3.

Conjectures from Colin Barker, Aug 20 2018: (Start)

G.f.: x*(1 - x)*(2 - 5*x) / (1 - 8*x + 10*x^2).

a(n) = (-(4-sqrt(6))^n*(-6+sqrt(6)) + (4+sqrt(6))^n*(6+sqrt(6))) / 40 for n>1.

(End)

EXAMPLE

Some solutions for n=3:

..0..1....0..1....0..0....0..0....0..1....0..1....0..1....0..1....0..1....0..1

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

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

CROSSREFS

Cf. A223387.

Sequence in context: A274393 A004103 A295775 * A175896 A175900 A175912

Adjacent sequences:  A223378 A223379 A223380 * A223382 A223383 A223384

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 19 2013

STATUS

approved

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Last modified October 25 07:16 EDT 2021. Contains 348239 sequences. (Running on oeis4.)