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A280668 Number of n X 3 0..2 arrays with no element equal to more than one of its horizontal and antidiagonal neighbors and with new values introduced in order 0 sequentially upwards. 1
4, 59, 858, 12484, 181640, 2642832, 38452768, 559481408, 8140361856, 118440917248, 1723295736320, 25073667646464, 364817712941056, 5308037322346496, 77231064216379392, 1123699197608083456 (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) = 14*a(n-1) + 8*a(n-2).

Conjectures from Colin Barker, Feb 14 2019: (Start)

G.f.: x*(4 + 3*x) / (1 - 14*x - 8*x^2).

a(n) = ((7-sqrt(57))^n*(-11+3*sqrt(57)) + (7+sqrt(57))^n*(11+3*sqrt(57))) / (16*sqrt(57)).

(End)

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Column 3 of A280673.

Sequence in context: A093597 A257069 A199107 * A198508 A126754 A264820

Adjacent sequences:  A280665 A280666 A280667 * A280669 A280670 A280671

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 07 2017

STATUS

approved

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Last modified November 30 03:03 EST 2021. Contains 349416 sequences. (Running on oeis4.)