A217631 Number of nX2 arrays of the minimum value of corresponding elements and their horizontal and vertical neighbors in a random 0..1 nX2 array.

0, 2, 6, 16, 38, 98, 244, 614, 1542, 3872, 9726, 24426, 61348, 154078, 386974, 971904, 2440982, 6130642, 15397396, 38671286, 97124758, 243933408, 612650254, 1538699994, 3864517572, 9705918062, 24376870766, 61223660096, 153766108518

Offset: 0

Author

R. H. Hardin Oct 09 2012

Keywords

• nonn

Comments

Also, number of maximal independent sets in the 3-dimensional (2, 2, n) grid graph. [Euler et al.] - N. J. A. Sloane, Nov 21 2013

Column 2 of A217637.

Examples

			Some solutions for n=3
..0..0....0..0....0..0....1..1....0..0....1..0....1..0....0..1....1..1....0..0
..0..1....0..0....0..1....0..1....1..0....0..0....0..0....0..0....1..1....1..0
..0..0....1..0....1..1....0..0....0..0....0..0....1..0....0..1....1..1....1..1
		

Links

• R. H. Hardin, Table of n, a(n) for n = 0..210
• R. Euler, P. Oleksik, Z. Skupien, Counting Maximal Distance-Independent Sets in Grid Graphs, Discussiones Mathematicae Graph Theory. Volume 33, Issue 3, Pages 531-557, ISSN (Print) 2083-5892, July 2013; http://www.degruyter.com/view/j/dmgt.2013.33.issue-3/dmgt.1707/dmgt.1707.xml

Crossrefs

Cf. A217632, A217637.

Formula

G.f. = (2*x+4*x^2+4*x^3)/(1-x-3*x^2-2*x^3). [Euler et al.] - N. J. A. Sloane, Nov 21 2013

Empirical: a(n) = a(n-1) + 3*a(n-2) + 2*a(n-3). (Follows from g.f. - N. J. A. Sloane, Nov 21 2013)