A221757 Number of 3 X n arrays of occupancy after each element moves to some horizontal or antidiagonal neighbor, without move-in move-out straight through or left turns.

0, 4, 0, 43, 44, 736, 1680, 14548, 47314, 307629, 1201506, 6768794, 29159864, 152481584, 692301668, 3481342319, 16253985408, 80073291120, 379418253880, 1849109113064, 8830193356854, 42791854403241, 205182113819686

Offset

1,2

Comments

Row 3 of A221755.

Links

R. H. Hardin, Table of n, a(n) for n = 1..73

Formula

Empirical: a(n) = 27*a(n-2) + 14*a(n-3) - 165*a(n-4) - 20*a(n-5) + 329*a(n-6) - 48*a(n-7) - 131*a(n-8) - 34*a(n-9) + 9*a(n-10).

Empirical g.f.: x^2*(4 - 65*x^2 - 12*x^3 + 235*x^4 - 30*x^5 - 161*x^6 - 38*x^7 + 10*x^8) / (1 - 27*x^2 - 14*x^3 + 165*x^4 + 20*x^5 - 329*x^6 + 48*x^7 + 131*x^8 + 34*x^9 - 9*x^10). - Colin Barker, Aug 10 2018

Example

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

Crossrefs

Cf. A221755.

Sequence in context: A271834 A138546 A019217 * A189424 A009371 A248952

Adjacent sequences: A221754 A221755 A221756 * A221758 A221759 A221760

Keyword

nonn

Author

R. H. Hardin, Jan 24 2013

Status

approved