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 A218836 Unmatched value maps: number of n X 2 binary arrays indicating the locations of corresponding elements not equal to any horizontal or antidiagonal neighbor in a random 0..1 n X 2 array. 10
 1, 2, 7, 21, 65, 200, 616, 1897, 5842, 17991, 55405, 170625, 525456, 1618192, 4983377, 15346786, 47261895, 145547525, 448227521, 1380359512, 4250949112, 13091204281, 40315615410, 124155792775, 382349636061, 1177482265857, 3626169232672, 11167134898976 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS R. H. Hardin, Table of n, a(n) for n = 0..210 Index entries for linear recurrences with constant coefficients, signature (2,3,1). FORMULA a(n) = 2*a(n-1) +3*a(n-2) +a(n-3). G.f.: Q(0)/2 , where Q(k) = 1 + 1/(1- x*(4*k+2 +3*x+x^2)/(x*(4*k+4 +3*x+x^2) + 1/Q(k+1))); (continued fraction). - Sergei N. Gladkovskii, Oct 04 2013 G.f.: 1/(1-2*x-3*x^2-x^3). - Alois P. Heinz, Apr 21 2020 EXAMPLE Some solutions for n=3 ..1..1....1..1....0..0....1..0....0..0....1..0....0..0....1..1....0..0....1..0 ..1..1....1..1....0..1....0..1....0..0....0..0....0..0....0..0....0..1....0..0 ..1..1....0..0....0..0....1..1....0..1....1..1....1..1....1..1....1..1....0..1 MAPLE a:= n-> (<<0|1|0>, <0|0|1>, <1|3|2>>^n. <<1, 2, 7>>)[1\$2]: seq(a(n), n=0..30); # Alois P. Heinz, Apr 21 2020 CROSSREFS Column 2 of A218842. Sequence in context: A106271 A027990 A037520 * A331722 A052911 A126133 Adjacent sequences: A218833 A218834 A218835 * A218837 A218838 A218839 KEYWORD nonn,easy AUTHOR R. H. Hardin, Nov 07 2012 EXTENSIONS a(0)=1 prepended and first g.f. adapted by Alois P. Heinz, Apr 21 2020 STATUS approved

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Last modified September 11 15:26 EDT 2024. Contains 375836 sequences. (Running on oeis4.)