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A274954

Number of n X 3 0..2 arrays with no element equal to any value at offset (-1,-1) (-2,0) or (0,-2) and new values introduced in order 0..2.

3, 24, 90, 384, 1638, 6936, 29370, 124416, 527046, 2232600, 9457434, 40062336, 169706790, 718889496, 3045264762, 12899948544, 54645058950, 231480184344, 980565796314, 4153743369600, 17595539274726, 74535900468504

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OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = 4*a(n-1) + 4*a(n-3) + a(n-4) for n>5.

Empirical g.f.: 3*x*(1 + 4*x - 2*x^2 + 4*x^3 + x^4) / ((1 + x^2)*(1 - 4*x - x^2)). - Colin Barker, Jan 31 2019

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Column 3 of A274959.

Sequence in context: A276243 A211618 A362345 * A156832 A092780 A004282

Adjacent sequences: A274951 A274952 A274953 * A274955 A274956 A274957

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jul 12 2016

STATUS

approved

URL: https://oeis.org/A274954

⇱ A274954 - OEIS