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.

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

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: A181457 A261380 A337861 * A248372 A349705 A129288

Adjacent sequences: A261370 A261371 A261372 * A261374 A261375 A261376

Keyword

nonn

Author

R. H. Hardin, Aug 17 2015

Status

approved