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A221088 Number of 2 X n arrays of occupancy after each element moves to some horizontal or antidiagonal neighbor. 1
0, 4, 24, 169, 1155, 7921, 54288, 372100, 2550408, 17480761, 119814915, 821223649, 5628750624, 38580030724, 264431464440, 1812440220361, 12422650078083, 85146110326225, 583600122205488, 4000054745112196, 27416783093579880 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Row 2 of A221087.

LINKS

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

FORMULA

Empirical: a(n) = 7*a(n-1) - 7*a(n-3) + a(n-4).

Empirical g.f.: x^2*(2 - x)^2 / ((1 - x)*(1 + x)*(1 - 7*x + x^2)). - Colin Barker, Aug 03 2018

EXAMPLE

Some solutions for n=3:

..0..1..0....0..1..1....1..2..0....1..3..1....1..1..0....1..3..0....1..2..1

..2..3..0....0..3..1....1..2..0....0..1..0....0..3..1....0..1..1....0..2..0

CROSSREFS

Cf. A221087.

Sequence in context: A246423 A188913 A052685 * A347651 A032349 A215709

Adjacent sequences:  A221085 A221086 A221087 * A221089 A221090 A221091

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 01 2013

STATUS

approved

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Last modified January 24 22:45 EST 2022. Contains 350565 sequences. (Running on oeis4.)