A221236 Number of n X 2 arrays of occupancy after each element moves to some horizontal, vertical or antidiagonal neighbor, without 2-loops.

0, 5, 53, 467, 3913, 32299, 265353, 2176758, 17847997, 146319703, 1199485661, 9832876386, 80605364957, 660764392260, 5416629053076, 44402915641056, 363993693602517, 2983844751876537, 24460120087308763, 200512266365651825

Offset

1,2

Comments

Column 2 of A221240.

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 11*a(n-1) - 23*a(n-2) - a(n-3) + 10*a(n-4) - a(n-6).

Empirical g.f.: x^2*(5 - 2*x - x^2) / ((1 - 3*x + x^2)*(1 - 8*x - 2*x^2 + 3*x^3 + x^4)). - Colin Barker, Aug 04 2018

Example

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

Crossrefs

Cf. A221240.

Sequence in context: A069617 A173879 A058390 * A198963 A293082 A069592

Adjacent sequences: A221233 A221234 A221235 * A221237 A221238 A221239

Keyword

nonn

Author

R. H. Hardin, Jan 06 2013

Status

approved