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A281401 Number of 2 X n 0..1 arrays with no element equal to more than two of its horizontal, diagonal or antidiagonal neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards. 1
0, 0, 10, 52, 170, 484, 1296, 3308, 8222, 19996, 47894, 113320, 265560, 617472, 1426498, 3277796, 7497418, 17082444, 38791072, 87831508, 198365446, 447006060, 1005324158, 2257048752, 5059420328, 11325490728, 25320461706, 56545544372 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

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

FORMULA

Empirical: a(n) = 4*a(n-1) + a(n-2) - 16*a(n-3) - a(n-4) + 30*a(n-5) + 4*a(n-6) - 24*a(n-7) - 4*a(n-8) + 8*a(n-9) for n>10.

Empirical g.f.: 2*x^3*(1 + 2*x - 2*x^3)*(5 - 4*x - 16*x^2 - 2*x^3 + 12*x^4) / ((1 - 2*x)*(1 - x - 3*x^2 + 2*x^4)^2). - Colin Barker, Feb 18 2019

EXAMPLE

Some solutions for n=4:

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

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

CROSSREFS

Row 2 of A281400.

Sequence in context: A028994 A257042 A092966 * A050494 A200035 A119543

Adjacent sequences:  A281398 A281399 A281400 * A281402 A281403 A281404

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 21 2017

STATUS

approved

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Last modified July 25 12:15 EDT 2021. Contains 346290 sequences. (Running on oeis4.)