A182798 - OEIS

A182798

Number of 4-colorings of the n X n X n triangular grid.

4, 24, 192, 2112, 32640, 718080, 22665216, 1031276544, 67849629696, 6468240187392, 894839431299072, 179851071814434816, 52561241074964496384, 22351071118387029737472, 13837189739906569661841408

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OFFSET

1,1

COMMENTS

The n X n X n triangular grid has n rows with k vertices in row k. Each vertex is connected to the neighbors in the same row and up to two vertices in each of the neighboring rows. The graph has A000217(n) vertices and 3*A000217(n-1) edges altogether.

LINKS

Table of n, a(n) for n=1..15.

Wikipedia, Chromatic polynomial

Wikipedia, Triangular grid graph

FORMULA

a(n) = 4 * A153467(n).

CROSSREFS

4th row of A182797. Cf. A178435, A182788, A182789, A182790, A182791, A182792, A182793, A182794, A182795, A182796.

Sequence in context: A365293 A293021 A002866 * A374852 A073840 A024249

Adjacent sequences: A182795 A182796 A182797 * A182799 A182800 A182801

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Dec 02 2010

EXTENSIONS

a(15) from Alois P. Heinz, Mar 11 2016

STATUS

approved