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A209225 Number of 4 X n 0..1 arrays avoiding 0 0 0 and 0 1 0 horizontally and 0 1 0 and 1 1 1 vertically. 1
9, 81, 126, 196, 504, 1296, 3312, 8464, 21712, 55696, 142544, 364816, 934992, 2396304, 6136272, 15713296, 40258384, 103144336, 264177872, 676624144, 1733335632, 4440356496, 11373699024, 29133027856, 74627823952, 191168323984 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 4 of A209224.

LINKS

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

FORMULA

Empirical: a(n) = a(n-1) + 4*a(n-3) + 16*a(n-4) for n>7.

Empirical g.f.: x*(9 + 72*x + 45*x^2 + 34*x^3 - 160*x^4 - 1008*x^5 - 784*x^6) / ((1 + 4*x^2)*(1 - x - 4*x^2)). - Colin Barker, Jul 08 2018

EXAMPLE

Some solutions for n=4:

  1 1 0 1     0 0 1 1     0 1 1 0     0 1 1 1     0 1 1 1

  1 1 0 0     1 1 0 0     0 1 1 0     0 1 1 0     0 0 1 1

  0 0 1 1     1 1 0 0     1 0 0 1     1 0 0 1     1 1 0 0

  0 0 1 1     0 0 1 1     1 1 0 1     1 1 1 1     1 1 0 0

CROSSREFS

Cf. A209224.

Sequence in context: A161147 A209220 A207689 * A208502 A175370 A207695

Adjacent sequences:  A209222 A209223 A209224 * A209226 A209227 A209228

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 06 2012

STATUS

approved

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Last modified December 1 14:10 EST 2021. Contains 349430 sequences. (Running on oeis4.)