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 A202882 Number of n X 1 0..2 arrays with every nonzero element less than or equal to some horizontal or vertical neighbor. 8
 1, 3, 9, 22, 51, 121, 292, 704, 1691, 4059, 9749, 23422, 56268, 135166, 324692, 779977, 1873673, 4500958, 10812237, 25973244, 62393157, 149881402, 360046432, 864906711, 2077686532, 4991036946, 11989513056, 28801314179, 69186771332 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 T. Mansour and M. Shattuck, Counting Peaks and Valleys in a Partition of a Set, J. Int. Seq. 13 (2010), 10.6.8, Lemma 2.1, k=3, one peak. FORMULA Empirical: a(n) = 3*a(n-1) -3*a(n-2) +4*a(n-3) -a(n-4) +a(n-5). Empirical: G.f.: -x*(1+3*x^2+x^4)/(-1+3*x-3*x^2+4*x^3-x^4+x^5). - R. J. Mathar, Jul 09 2017 EXAMPLE Some solutions for n=5 ..2....2....1....0....2....2....0....1....0....1....1....0....2....1....0....2 ..2....2....1....1....2....2....2....1....2....2....1....0....2....2....1....2 ..0....1....1....2....0....2....2....0....2....2....1....1....1....2....1....0 ..0....1....1....2....1....1....2....0....0....0....2....1....2....2....2....2 ..0....0....1....2....1....1....1....0....0....0....2....1....2....0....2....2 CROSSREFS Column 1 of A202889. Sequence in context: A099166 A222083 A305612 * A350105 A336511 A054442 Adjacent sequences: A202879 A202880 A202881 * A202883 A202884 A202885 KEYWORD nonn AUTHOR R. H. Hardin, Dec 25 2011 STATUS approved

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Last modified May 24 23:50 EDT 2024. Contains 372782 sequences. (Running on oeis4.)