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A209101 Number of 2 X n 0..2 arrays with new values 0..2 introduced in row major order and no element equal to more than one of its immediate leftward or upward or right-upward antidiagonal neighbors. 1
2, 11, 76, 520, 3552, 24256, 165632, 1131008, 7723008, 52736000, 360103936, 2458943488, 16790716416, 114654183424, 782907736064, 5346028421120, 36504965480448, 249271496474624, 1702132247953408, 11622886011830272 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 2 of A209100.

LINKS

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

FORMULA

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

Empirical g.f.: x*(2 - 5*x + 4*x^2) / (1 - 8*x + 8*x^2). - Colin Barker, Jul 08 2018

EXAMPLE

Some solutions for n=4:

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

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

CROSSREFS

Cf. A209100.

Sequence in context: A220878 A049363 A055085 * A118802 A053481 A110329

Adjacent sequences:  A209098 A209099 A209100 * A209102 A209103 A209104

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 05 2012

STATUS

approved

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Last modified March 31 03:48 EDT 2020. Contains 333136 sequences. (Running on oeis4.)