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A260131 Number of (n+2) X (1+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00010101 01010101 or 01010111. 1
36, 58, 138, 266, 472, 944, 1880, 3562, 6866, 13450, 26016, 50176, 97392, 188890, 365434, 707786, 1371848, 2657040, 5145832, 9969162, 19312130, 37406666, 72459984, 140365536, 271897664, 526684282, 1020240874, 1976299402, 3828249912 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = a(n-1) + 3*a(n-3) + a(n-4) for n>5.

Empirical g.f.: 2*x*(18 + 11*x + 40*x^2 + 10*x^3 - 2*x^4) / (1 - x - 3*x^3 - x^4). - Colin Barker, Dec 28 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

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

CROSSREFS

Column 1 of A260138.

Sequence in context: A080469 A341283 A260138 * A320632 A188633 A328961

Adjacent sequences:  A260128 A260129 A260130 * A260132 A260133 A260134

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jul 17 2015

STATUS

approved

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Last modified January 18 17:18 EST 2022. Contains 350455 sequences. (Running on oeis4.)