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A261373 Number of (n+2) X (1+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00001011 00010101 or 01010101. 1
36, 39, 60, 97, 154, 247, 392, 618, 977, 1548, 2461, 3894, 6176, 9774, 15513, 24552, 38963, 61662, 97854, 154866, 245769, 388956, 617257, 976878, 1550272, 2453478, 3893581, 6162024, 9778911, 15476214, 24560198, 38869242, 61684093, 97621932 (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>12.

Empirical g.f.: x*(36 + 39*x + 24*x^2 + 58*x^3 - 14*x^4 + 33*x^5 - 14*x^6 + 2*x^7 + 3*x^8 - 5*x^9 - 2*x^11) / (1 - x^2 - 3*x^4 - 2*x^6). - Colin Barker, Dec 30 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

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

CROSSREFS

Column 1 of A261380.

Sequence in context: A257441 A181457 A261380 * A248372 A129288 A083248

Adjacent sequences:  A261370 A261371 A261372 * A261374 A261375 A261376

KEYWORD

nonn

AUTHOR

R. H. Hardin, Aug 17 2015

STATUS

approved

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Last modified September 20 03:14 EDT 2020. Contains 337262 sequences. (Running on oeis4.)