A221122 Number of n X 4 arrays of occupancy after each element stays put or moves to some horizontal or antidiagonal neighbor.

21, 1950, 179300, 16436223, 1506094707, 138001217828, 12644783009532, 1158616222843158, 106161685080363377, 9727382617196220288, 891300589691816054472, 81668088157651470747218, 7483083373227566657384892

Offset

1,1

Comments

Column 4 of A221125.

Links

R. H. Hardin, Table of n, a(n) for n = 1..18

Formula

Empirical: a(n) = 109*a(n-1) - 1680*a(n-2) + 8230*a(n-3) - 13300*a(n-4) + 2025*a(n-5) for n>6.

Empirical g.f.: x*(21 - 339*x + 2030*x^2 - 4307*x^3 + 1200*x^4 + 2880*x^5) / (1 - 109*x + 1680*x^2 - 8230*x^3 + 13300*x^4 - 2025*x^5). - Colin Barker, Aug 03 2018

Example

Some solutions for n=3:
  1 1 1 0     0 3 1 1     0 2 0 2     1 1 0 1     1 0 2 0
  1 2 1 1     1 1 1 2     1 3 0 1     0 1 3 0     0 3 4 0
  0 1 3 0     0 1 0 1     0 0 1 2     0 3 1 1     0 1 1 0

Crossrefs

Cf. A221125.

Sequence in context: A163928 A358803 A243685 * A265175 A300577 A304643

Adjacent sequences: A221119 A221120 A221121 * A221123 A221124 A221125

Keyword

nonn

Author

R. H. Hardin, Jan 02 2013

Status

approved