A207753 Number of 4 X n 0..1 arrays avoiding 0 0 1 and 0 1 1 horizontally and 0 0 1 and 1 0 0 vertically.

9, 81, 270, 900, 2100, 4900, 9450, 18225, 31185, 53361, 84084, 132496, 196560, 291600, 413100, 585225, 799425, 1092025, 1448370, 1920996, 2486484, 3218436, 4081350, 5175625, 6449625, 8037225, 9865800, 12110400, 14671680, 17774656

Offset

1,1

Comments

Row 4 of A207752.

Links

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

Formula

Empirical: a(n) = 2*a(n-1) + 4*a(n-2) - 10*a(n-3) - 5*a(n-4) + 20*a(n-5) - 20*a(n-7) + 5*a(n-8) + 10*a(n-9) - 4*a(n-10) - 2*a(n-11) + a(n-12).

Empirical g.f.: x*(9 + 63*x + 72*x^2 + 126*x^3 + 75*x^4 + 25*x^5 - 20*x^6 + 5*x^7 + 10*x^8 - 4*x^9 - 2*x^10 + x^11) / ((1 - x)^7*(1 + x)^5). - Colin Barker, Jun 25 2018

Example

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

Crossrefs

Cf. A207752.

Sequence in context: A208421 A209646 A267715 * A207107 A207463 A207914

Adjacent sequences: A207750 A207751 A207752 * A207754 A207755 A207756

Keyword

nonn

Author

R. H. Hardin, Feb 19 2012

Status

approved