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A240784 Number of 3 X n 0..1 arrays with no element equal to fewer vertical neighbors than horizontal neighbors, with new values 0..1 introduced in row major order. 1
4, 11, 20, 46, 97, 216, 472, 1043, 2296, 5066, 11169, 24636, 54332, 119835, 264300, 582934, 1285697, 2835696, 6254320, 13794339, 30424368, 67103058, 148000449, 326425268, 719953588, 1587907627, 3502240516, 7724434622, 17036776865 (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) = 2*a(n-1) + a(n-2) - a(n-3) - a(n-5).

Empirical g.f.: x*(4 + 3*x - 6*x^2 - x^3 - 4*x^4) / ((1 - x)*(1 + x)*(1 - 2*x - x^3)). - Colin Barker, Oct 29 2018

EXAMPLE

Some solutions for n=4:

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

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

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

CROSSREFS

Row 3 of A240783.

Sequence in context: A008174 A008262 A075099 * A297961 A240155 A161975

Adjacent sequences:  A240781 A240782 A240783 * A240785 A240786 A240787

KEYWORD

nonn

AUTHOR

R. H. Hardin, Apr 12 2014

STATUS

approved

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Last modified March 21 22:19 EDT 2019. Contains 321382 sequences. (Running on oeis4.)