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A208310 Number of n X 4 0..1 arrays with new values 0..1 introduced in row major order and no element equal to more than one of its immediate leftward or upward neighbors. 1
8, 54, 336, 2052, 12474, 75744, 459810, 2791152, 16942716, 102844566, 624279960, 3789460422, 23002516080, 139628253924, 847561596858, 5144808733200, 31229655752466, 189568057623696, 1150702676836956, 6984914373637974 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 4 of A208314.

LINKS

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

FORMULA

Empirical: a(n) = 9*a(n-1) - 21*a(n-2) + 21*a(n-3) - 9*a(n-4).

Empirical g.f.: 2*x*(4 - 9*x + 9*x^2 - 3*x^3) / (1 - 9*x + 21*x^2 - 21*x^3 + 9*x^4). - Colin Barker, Jun 30 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Cf. A208314.

Sequence in context: A091433 A081899 A057970 * A154235 A289796 A287814

Adjacent sequences:  A208307 A208308 A208309 * A208311 A208312 A208313

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 25 2012

STATUS

approved

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Last modified May 18 14:41 EDT 2022. Contains 353816 sequences. (Running on oeis4.)