A216990 Number of city-block distance 1, pressure limit 2 movements in an nX7 array with each element moving exactly one horizontally or vertically, no element acquiring more than two neighbors, and without 2-loops

0, 12578, 24673352, 49491906456, 94821314531592, 180328865345987360, 342045101062468307160, 648338338792898616469226, 1228659499592627438742733120, 2328285492440707317251867198066

Offset

1,2

Comments

Column 7 of A216991

Links

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

Example

Some solutions for n=3 (movement: 0=n 1=e 2=s 3=w)
..2..2..2..2..3..1..2....2..2..2..2..1..2..3....2..2..2..2..3..2..3
..1..1..2..1..2..3..3....1..1..2..1..0..3..0....2..1..2..2..3..2..0
..0..3..3..0..1..0..3....0..3..3..3..3..3..3....1..0..1..1..0..3..0

Crossrefs

Sequence in context: A205757 A205587 A235103 * A237086 A190109 A272516

Adjacent sequences: A216987 A216988 A216989 * A216991 A216992 A216993

Keyword

nonn

Author

R. H. Hardin Sep 21 2012

Status

approved