A068271 1/4 the number of colorings of an n X n rhombic hexagonal array with 4 colors.

1, 12, 264, 11424, 1008576, 184910592, 71033971200, 57469424744448, 98237339264864256, 355574469749489123328, 2729407814499050197254144, 44482040254775494064841818112, 1540473331004371306422199656382464, 113440401780206156918876627438624833536

Offset: 1

Author

R. H. Hardin, Feb 24 2002

Keywords

• nonn

Comments

Terms for rhombic- and staggered- hexagonal arrays are the same for n in 1..4.

Links

• Andrew Howroyd, Table of n, a(n) for n = 1..16

Crossrefs

Cf. A068239-A068305, A000332, A002417, A027441, A212162, A212163.

Extensions

a(9) from Alois P. Heinz, May 02 2012

a(10)-a(14) from Andrew Howroyd, Jun 25 2017