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A259735 Number of (n+2) X (1+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00010101 or 01010101. 1
20, 22, 42, 62, 101, 152, 265, 382, 652, 962, 1649, 2412, 4135, 6062, 10386, 15222, 26089, 38232, 65517, 96022, 164556, 241162, 413285, 605692, 1037987, 1521222, 2606954, 3820622, 6547485, 9595672, 16444321, 24099982, 41300684, 60528242 (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-2) + 3*a(n-4) + 2*a(n-6) for n>7.

Empirical g.f.: x*(20 + 22*x + 22*x^2 + 40*x^3 - x^4 + 24*x^5 - 2*x^6) / (1 - x^2 - 3*x^4 - 2*x^6). - Colin Barker, Dec 26 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

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

CROSSREFS

Column 1 of A259742.

Sequence in context: A171953 A133260 A163630 * A033906 A322323 A139357

Adjacent sequences:  A259732 A259733 A259734 * A259736 A259737 A259738

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jul 04 2015

STATUS

approved

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Last modified April 25 00:29 EDT 2019. Contains 322446 sequences. (Running on oeis4.)