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 A183897 Number of nondecreasing arrangements of n+3 numbers in 0..2 with each number being the sum mod 3 of three others. 1
 1, 7, 17, 25, 34, 44, 55, 67, 80, 94, 109, 125, 142, 160, 179, 199, 220, 242, 265, 289, 314, 340, 367, 395, 424, 454, 485, 517, 550, 584, 619, 655, 692, 730, 769, 809, 850, 892, 935, 979, 1024, 1070, 1117, 1165, 1214, 1264, 1315, 1367, 1420, 1474, 1529, 1585, 1642 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Column 2 of A183904. LINKS R. H. Hardin, Table of n, a(n) for n = 1..62 Charles Cratty, Samuel Erickson, Frehiwet Negass, Lara Pudwell, Pattern Avoidance in Double Lists, preprint, 2015. FORMULA Empirical: a(n) = (1/2)*n^2 + (9/2)*n - 1 for n>2. Conjectures from Colin Barker, Apr 05 2018: (Start) G.f.: x*(1 + x - x^2)*(1 + 3*x - 3*x^2) / (1 - x)^3. a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>5. (End) EXAMPLE Some solutions for n=4: ..0....0....0....0....1....0....0....0....1....0....0....0....0....0....0....0 ..1....1....0....0....1....0....0....0....1....0....0....0....0....0....1....0 ..1....1....2....0....1....0....1....0....1....0....1....0....0....1....1....1 ..2....1....2....0....2....1....1....0....1....1....1....0....0....1....1....1 ..2....1....2....1....2....1....1....2....2....2....2....0....1....1....1....1 ..2....2....2....1....2....1....1....2....2....2....2....1....2....1....1....2 ..2....2....2....1....2....1....1....2....2....2....2....1....2....2....2....2 CROSSREFS Cf. A183904. Sequence in context: A263264 A072199 A309231 * A300186 A261934 A253075 Adjacent sequences:  A183894 A183895 A183896 * A183898 A183899 A183900 KEYWORD nonn AUTHOR R. H. Hardin, Jan 07 2011 STATUS approved

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Last modified December 3 16:20 EST 2020. Contains 338906 sequences. (Running on oeis4.)