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A280599 Number of n X 3 0..1 arrays with no element equal to more than two of its horizontal, vertical and antidiagonal neighbors and with new values introduced in order 0 sequentially upwards. 2
4, 18, 45, 116, 293, 735, 1844, 4626, 11611, 29151, 73200, 183828, 461671, 1159483, 2912066, 7313756, 18368803, 46134069, 115867838, 291007480, 730878941, 1835636845, 4610288394, 11578956554, 29081095145, 73038541289, 183439739500 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A280604.

LINKS

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

FORMULA

Empirical: a(n) = 4*a(n-1) - 3*a(n-2) - 3*a(n-3) + 2*a(n-4) + 3*a(n-5) - 2*a(n-6) for n>8.

Empirical g.f.: x*(4 + 2*x - 15*x^2 + 2*x^3 + 10*x^4 - 2*x^5 - 5*x^6 + 3*x^7) / ((1 - x)^3*(1 - x - 3*x^2 - 2*x^3)). - Colin Barker, Mar 22 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Cf. A280604.

Sequence in context: A115077 A278046 A258634 * A066153 A213926 A023650

Adjacent sequences:  A280596 A280597 A280598 * A280600 A280601 A280602

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 06 2017

STATUS

approved

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Last modified July 27 07:36 EDT 2021. Contains 346304 sequences. (Running on oeis4.)