A216832 Number of city-block distance 1 permutations of a side-n hexagonal array.

0, 36, 198576, 427073321712, 160091486928671945664

Offset

1,2

Links

Table of n, a(n) for n=1..5.

Example

Some solutions for n=3 (movement: 0=nw 1=ne 2=e 3=se 4=sw 5=w)
...3.3.3.......2.5.3.......3.2.5.......3.2.3.......2.4.3
..1.1.1.3.....4.5.4.0.....4.0.4.3.....4.0.0.5.....3.0.4.0
.1.3.2.4.4...3.1.1.2.5...1.3.1.3.0...1.4.2.4.4...1.5.2.0.4
..0.0.0.4.....1.4.2.5.....3.0.4.0.....1.1.3.1.....3.2.5.1
...0.5.5.......1.2.5.......0.2.0.......1.5.5.......0.2.5

Crossrefs

Sequence in context: A203270 A185960 A334409 * A013839 A271386 A065752

Adjacent sequences: A216829 A216830 A216831 * A216833 A216834 A216835

Keyword

nonn,hard,more

Author

R. H. Hardin Sep 17 2012

Status

approved