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 A223408 4 X 4 X 4 triangular graph without horizontal edges coloring a rectangular array: number of n X 1 0..9 arrays where 0..9 label nodes of a graph with edges 0,1 0,2 1,3 1,4 2,4 2,5 3,6 3,7 4,7 4,8 5,8 5,9 and every array movement to a horizontal or vertical neighbor moves along an edge of this graph. 1
 10, 24, 66, 176, 486, 1312, 3622, 9792, 27030, 73088, 201750, 545536, 1505878, 4071936, 11240022, 30393344, 83896662, 226859008, 626213206, 1693298688, 4674118998, 12638953472, 34888099158, 94338433024, 260408317270 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Column 1 of A223415. LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 9*a(n-2) - 12*a(n-4) + 4*a(n-6). Empirical g.f.: 2*x*(5 + 12*x - 12*x^2 - 20*x^3 + 6*x^4 + 8*x^5) / ((1 - x)*(1 + x)*(1 + 2*x - 2*x^2)*(1 - 2*x - 2*x^2)). - Colin Barker, Aug 20 2018 EXAMPLE Some solutions for n=3: ..1....7....4....4....8....2....5....4....1....2....4....4....3....4....1....6 ..4....4....7....8....4....0....2....2....0....4....8....1....6....2....4....3 ..1....8....3....5....7....1....4....0....1....8....4....0....3....5....2....1 CROSSREFS Cf. A223415. Sequence in context: A250798 A250576 A126911 * A261807 A135285 A235940 Adjacent sequences:  A223405 A223406 A223407 * A223409 A223410 A223411 KEYWORD nonn AUTHOR R. H. Hardin, Mar 20 2013 STATUS approved

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Last modified December 8 05:44 EST 2021. Contains 349590 sequences. (Running on oeis4.)