A027740 Number of independent subsets of nodes in graph formed from n-fold subdivision of triangle.

1, 2, 4, 14, 60, 384, 3318, 40638, 689636, 16383974, 542420394, 25075022590, 1617185558560, 145563089994148, 18283036276489970, 3204638749437865046, 783848125594781710150, 267554112823378352976752

Offset

0,2

Comments

In other words, number of independent vertex sets (and vertex covers) in the (n-1)-triangular grid graph. - Eric W. Weisstein, Jun 14 2017

Number of planar n X n X n binary triangular grids with no more than 1 one in any similarly oriented 2 X 2 X 2 subtriangle. - R. H. Hardin, Dec 27 2008

Links

Table of n, a(n) for n=0..17.

Eric Weisstein's World of Mathematics, Independent Vertex Set

Eric Weisstein's World of Mathematics, Triangular Grid Graph

Eric Weisstein's World of Mathematics, Vertex Cover

Crossrefs

Cf. A239567, A239438, A287064.

Sequence in context: A030938 A030808 A047009 * A132880 A019537 A046911

Adjacent sequences: A027737 A027738 A027739 * A027741 A027742 A027743

Keyword

nonn,nice

Author

R. H. Hardin

Status

approved