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 A198900 Number of n X 2 0..4 arrays with values 0..4 introduced in row major order and no element equal to any horizontal or vertical neighbor. 5
 1, 4, 33, 380, 4801, 62004, 804833, 10459180, 135958401, 1767426404, 22976444833, 298693487580, 3883014452801, 50479185229204, 656229400008033, 8530982176189580, 110902768218720001, 1441735986628126404 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Column 2 of A198906. LINKS R. H. Hardin, Table of n, a(n) for n = 1..200 FORMULA Empirical: a(n) = 17*a(n-1) -55*a(n-2) +39*a(n-3). Conjectures from Colin Barker, Feb 18 2018: (Start) G.f.: x*(1 - 13*x + 20*x^2) / ((1 - x)*(1 - 3*x)*(1 - 13*x)). a(n) = (26 + 13*3^n + 13^n) / 78. (End) EXAMPLE Some solutions with values 0 to 4 for n=4: ..0..1....0..1....0..1....0..1....0..1....0..1....0..1....0..1....0..1....0..1 ..2..3....2..3....2..0....1..2....1..0....2..3....2..3....2..3....1..2....2..3 ..4..2....1..4....3..2....3..1....2..3....1..4....3..1....4..2....2..3....4..0 ..2..4....3..2....4..3....2..4....4..2....4..3....4..2....2..0....4..0....0..3 CROSSREFS Sequence in context: A208961 A113170 A187738 * A166906 A293020 A293193 Adjacent sequences: A198897 A198898 A198899 * A198901 A198902 A198903 KEYWORD nonn AUTHOR R. H. Hardin, Oct 31 2011 STATUS approved

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Last modified September 18 07:20 EDT 2024. Contains 375996 sequences. (Running on oeis4.)