A221083 Number of n X 4 arrays of occupancy after each element moves to some horizontal or antidiagonal neighbor.

4, 169, 6889, 279841, 11363641, 461433361, 18736955689, 760832274049, 30894332043289, 1254494297783281, 50939956897994761, 2068466324059544161, 83992079976098560249, 3410579817835188926929, 138489899251625571693289

Offset

1,1

Comments

Column 4 of A221087.

Links

R. H. Hardin, Table of n, a(n) for n = 1..25

Formula

Empirical: a(n) = 45*a(n-1) - 180*a(n-2) + 64*a(n-3).

Empirical g.f.: x*(4 - 11*x + 4*x^2) / ((1 - 4*x)*(1 - 41*x + 16*x^2)). - Colin Barker, Aug 03 2018

Example

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

Crossrefs

Cf. A221087.

Sequence in context: A017414 A051476 A283566 * A355883 A181191 A306402

Adjacent sequences: A221080 A221081 A221082 * A221084 A221085 A221086

Keyword

nonn

Author

R. H. Hardin, Jan 01 2013

Status

approved