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A281464 Number of n X 3 0..1 arrays with no element equal to more than two of its horizontal, diagonal or antidiagonal neighbors and with new values introduced in order 0 sequentially upwards. 1
4, 17, 24, 60, 133, 283, 634, 1419, 3092, 6849, 15213, 33509, 74017, 163898, 361980, 799660, 1768383, 3908128, 8635736, 19089245, 42191413, 93242838, 206088583, 455499706, 1006707139, 2224999897, 4917670483, 10868814633, 24021891696 (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) + 3*a(n-3) - 3*a(n-4) - 4*a(n-5) + 4*a(n-6) - 4*a(n-7) for n>9.

Empirical g.f.: x*(4 + 9*x - 10*x^2 - 26*x^4 + 12*x^5 + 12*x^6 - 24*x^7 + 16*x^8) / (1 - 2*x - 3*x^3 + 3*x^4 + 4*x^5 - 4*x^6 + 4*x^7). - Colin Barker, Feb 19 2019

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Column 3 of A281469.

Sequence in context: A022134 A041529 A042033 * A192197 A009226 A273022

Adjacent sequences: A281461 A281462 A281463 * A281465 A281466 A281467

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 22 2017

STATUS

approved

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Last modified November 29 18:13 EST 2022. Contains 358431 sequences. (Running on oeis4.)