A221352 Number of 2 X n arrays of occupancy after each element moves to some horizontal, diagonal or antidiagonal neighbor, without 2-loops.

0, 1, 18, 148, 1164, 8824, 65932, 489456, 3622896, 26780480, 197840840, 1461141856, 10789799120, 79672591776, 588291947152, 4343817165312, 32073601733504, 236822417610560, 1748627793559200, 12911351644960960, 95333587133290624

Offset

1,3

Comments

Row 2 of A221351.

Links

R. H. Hardin, Table of n, a(n) for n = 1..40

Formula

Empirical: a(n) = 11*a(n-1) -26*a(n-2) -10*a(n-3) +34*a(n-4) +14*a(n-5) -16*a(n-6) -8*a(n-7).

Empirical g.f.: x^2*(1 + 7*x - 24*x^2 + 14*x^3 + 14*x^4 - 14*x^5) / (1 - 11*x + 26*x^2 + 10*x^3 - 34*x^4 - 14*x^5 + 16*x^6 + 8*x^7). - Colin Barker, Feb 12 2018

Example

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

Crossrefs

Sequence in context: A036397 A247741 A224329 * A271755 A197214 A027182

Adjacent sequences: A221349 A221350 A221351 * A221353 A221354 A221355

Keyword

nonn

Author

R. H. Hardin, Jan 11 2013

Status

approved