A185562 1/4 the number of n X 4 0..3 arrays with no element equal both to the element above and to the element to its left.

64, 13500, 2842560, 598507920, 126017211780, 26533211918040, 5586628402633500, 1176277376648694960, 247667889663690066720, 52147040135402715629580, 10979678466093753927519840, 2311796391622216326875508300

Offset

1,1

Comments

Column 4 of A185567.

Links

R. H. Hardin, Table of n, a(n) for n = 1..200

Formula

Empirical: a(n) = 217*a(n-1) - 1371*a(n-2) + 2835*a(n-3) - 2025*a(n-4).

Empirical g.f.: 4*x*(16 - 97*x + 201*x^2 - 135*x^3) / (1 - 217*x + 1371*x^2 - 2835*x^3 + 2025*x^4). - Colin Barker, Apr 16 2018

Example

Some solutions for 3 X 4 with a(1,1)=0:
..0..0..2..0....0..0..3..0....0..2..0..2....0..0..3..1....0..2..2..0
..0..2..0..3....2..0..3..2....0..2..0..2....2..2..2..2....0..2..0..2
..0..3..3..2....2..2..1..2....2..3..2..1....0..3..0..0....0..2..3..2

Crossrefs

Cf. A185567.

Sequence in context: A220300 A316485 A292025 * A264127 A135788 A016794

Adjacent sequences: A185559 A185560 A185561 * A185563 A185564 A185565

Keyword

nonn

Author

R. H. Hardin, Jan 31 2011

Status

approved