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A164755 Number of nX3 1..4 arrays with all 1s connected, all 2s connected, all 3s connected, all 4s connected, 1 in the upper left corner, 2 in the upper right corner, 3 in the lower left corner, 4 in the lower right corner, and with no element having more than 2 neighbors with the same value 0
8, 80, 258, 480, 644, 752, 850, 956, 1070, 1184, 1298, 1412, 1526, 1640, 1754, 1868, 1982, 2096, 2210, 2324, 2438, 2552, 2666, 2780, 2894, 3008, 3122, 3236, 3350, 3464, 3578, 3692, 3806, 3920, 4034, 4148, 4262 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

LINKS

Table of n, a(n) for n=2..38.

FORMULA

Empirical: a(n)=2*a(n-1)-a(n-2) for n>=11

EXAMPLE

Some solutions for n=4

...1.1.2...1.1.2...1.2.2...1.2.2...1.1.2...1.2.2...1.2.2...1.2.2...1.4.2

...1.1.2...3.2.2...1.2.4...1.3.4...1.2.2...2.2.3...1.2.2...1.1.4...1.4.2

...3.4.2...3.2.4...2.2.4...1.3.4...3.3.4...3.3.3...1.4.4...3.1.4...1.4.2

...3.4.4...3.4.4...3.4.4...3.3.4...3.3.4...3.4.4...3.3.4...3.4.4...3.4.4

------

...1.2.2...1.1.2...1.2.2...1.2.2...1.1.2...1.1.2...1.1.2...1.2.2...1.1.2

...3.3.2...3.1.2...1.1.2...1.1.2...1.4.2...1.2.2...3.1.2...1.1.2...2.2.2

...3.4.2...3.2.2...3.1.2...3.1.2...1.4.2...1.2.4...3.2.2...3.1.4...2.4.4

...3.4.4...3.3.4...3.3.4...3.1.4...3.4.4...3.4.4...3.4.4...3.1.4...3.3.4

CROSSREFS

Sequence in context: A069543 A144410 A188149 * A050799 A100431 A173116

Adjacent sequences:  A164752 A164753 A164754 * A164756 A164757 A164758

KEYWORD

nonn

AUTHOR

R. H. Hardin Aug 24 2009

STATUS

approved

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Last modified August 22 12:27 EDT 2019. Contains 326177 sequences. (Running on oeis4.)