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A241371 Number of 2 X n 0..2 arrays with no element equal to fewer vertical neighbors than horizontal neighbors, with new values 0..2 introduced in row major order. 1
2, 7, 28, 121, 523, 2261, 9775, 42261, 182711, 789933, 3415199, 14765285, 63836295, 275990109, 1193216815, 5158758677, 22303399319, 96426611981, 416891226559, 1802389311557, 7792457656743, 33689944754365, 145655251212111 (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) = 5*a(n-1) - 2*a(n-2) - 4*a(n-3) for n>5.

Empirical g.f.: x*(1 - x - x^2)*(2 - x - 2*x^2) / (1 - 5*x + 2*x^2 + 4*x^3). - Colin Barker, Oct 30 2018

EXAMPLE

Some solutions for n=4:

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

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

CROSSREFS

Row 2 of A241370.

Sequence in context: A150657 A150658 A026770 * A010683 A276852 A293266

Adjacent sequences:  A241368 A241369 A241370 * A241372 A241373 A241374

KEYWORD

nonn

AUTHOR

R. H. Hardin, Apr 20 2014

STATUS

approved

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Last modified February 19 00:35 EST 2020. Contains 332028 sequences. (Running on oeis4.)