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 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 6
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 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. 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 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) EXAMPLE 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 CROSSREFS Cf. A217632, A217637. Sequence in context: A330886 A265758 A265107 * A046209 A285885 A273348 Adjacent sequences: A217628 A217629 A217630 * A217632 A217633 A217634 KEYWORD nonn AUTHOR R. H. Hardin Oct 09 2012 STATUS approved

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Last modified June 5 18:54 EDT 2023. Contains 363138 sequences. (Running on oeis4.)