A207172 Number of 4 X n 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 0 1 and 1 0 1 vertically.

8, 64, 168, 603, 1612, 3952, 11452, 32021, 84300, 231616, 641775, 1736910, 4732822, 12996466, 35450695, 96651608, 264382416, 722256895, 1971272340, 5385783204, 14714016328, 40180554949, 109749174712, 299799902720, 818831131779

Offset

1,1

Comments

Row 4 of A207169.

Links

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

Formula

Empirical: a(n) = a(n-1) + 13*a(n-3) + 3*a(n-4) + 3*a(n-5) - 27*a(n-6) - 18*a(n-7) + 27*a(n-9) for n>11.

Empirical g.f.: x*(8 + 56*x + 104*x^2 + 331*x^3 + 153*x^4 - 60*x^5 - 819*x^6 - 828*x^7 - 54*x^8 + 837*x^9 + 324*x^10) / ((1 - x - 13*x^3 - 3*x^4 - 3*x^5 + 27*x^6 + 18*x^7 - 27*x^9)). - Colin Barker, Jun 20 2018

Example

Some solutions for n=4:
..1..0..0..1....1..1..0..0....1..1..1..1....0..1..0..0....0..0..1..1
..0..1..1..1....0..0..1..0....0..1..1..1....0..1..0..0....0..1..0..0
..0..0..1..1....0..0..1..0....0..1..1..0....0..1..0..0....0..1..0..0
..0..0..1..0....0..0..1..0....0..0..1..0....0..1..0..0....0..1..0..0

Crossrefs

Cf. A207169.

Sequence in context: A153808 A207601 A207027 * A207455 A207307 A207113

Adjacent sequences: A207169 A207170 A207171 * A207173 A207174 A207175

Keyword

nonn

Author

R. H. Hardin, Feb 15 2012

Status

approved