A221751 Number of nX4 arrays of occupancy after each element moves to some horizontal or antidiagonal neighbor, without move-in move-out straight through or left turns

1, 9, 43, 241, 1397, 7989, 45956, 264378, 1520571, 8746983, 50315631, 289432219, 1664916443, 9577180972, 55091295173, 316904423483, 1822945187570

Offset

1,2

Comments

Column 4 of A221755

Links

Table of n, a(n) for n=1..17.

Formula

Empirical: a(n) = 5*a(n-1) +5*a(n-2) +a(n-3) -27*a(n-4) -7*a(n-5) +7*a(n-6) +2*a(n-7) -a(n-8)

Example

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

Crossrefs

Sequence in context: A281773 A220676 A110125 * A275793 A223647 A034194

Adjacent sequences: A221748 A221749 A221750 * A221752 A221753 A221754

Keyword

nonn

Author

R. H. Hardin Jan 24 2013

Status

approved