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A274854 Number of n X 4 0..2 arrays with no element equal to any value at offset (-1,0) (0,-1) or (-2,-2) and new values introduced in order 0..2. 1
4, 27, 43, 118, 330, 923, 2585, 7253, 20368, 57205, 160656, 451182, 1267101, 3558565, 9994005, 28067514, 78825751, 221376890, 621722366, 1746066251, 4903711869, 13771751157, 38677054168, 108621953977, 305057588980, 856734105714 (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) - 9*a(n-2) + 10*a(n-3) - 6*a(n-4) + a(n-5) for n>7.

Empirical g.f.: x*(4 + 7*x - 56*x^2 + 106*x^3 - 119*x^4 + 63*x^5 - 9*x^6) / ((1 - x)*(1 - 4*x + 5*x^2 - 5*x^3 + x^4)). - Colin Barker, Jan 31 2019

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Column 4 of A274858.

Sequence in context: A129204 A239283 A082872 * A054411 A051506 A347671

Adjacent sequences: A274851 A274852 A274853 * A274855 A274856 A274857

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jul 09 2016

STATUS

approved

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Last modified January 27 21:49 EST 2023. Contains 359849 sequences. (Running on oeis4.)