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A068271 1/4 the number of colorings of an n X n rhombic hexagonal array with 4 colors. 4
1, 12, 264, 11424, 1008576, 184910592, 71033971200, 57469424744448, 98237339264864256, 355574469749489123328, 2729407814499050197254144, 44482040254775494064841818112, 1540473331004371306422199656382464, 113440401780206156918876627438624833536 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

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.

Sequence in context: A259269 A035265 A167869 * A068283 A003390 A239779

Adjacent sequences:  A068268 A068269 A068270 * A068272 A068273 A068274

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 24 2002

EXTENSIONS

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

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

STATUS

approved

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Last modified December 6 21:48 EST 2019. Contains 329809 sequences. (Running on oeis4.)