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 A240638 Number of n X 3 0..3 arrays with no element equal to one or three horizontal or vertical neighbors, with new values 0..3 introduced in row major order. 1
 2, 27, 462, 7993, 138882, 2413198, 41931738, 728606311, 12660271050, 219985006177, 3822461834214, 66419137967410, 1154099656091538, 20053648044092851, 348452404221602982, 6054712725626870185 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 14*a(n-1) + 54*a(n-2) + 82*a(n-3) - 14*a(n-4) - 54*a(n-5) - 81*a(n-6). Empirical g.f.: x*(2 - x - 24*x^2 - 97*x^3 - 154*x^4 - 170*x^5) / ((1 - x)*(1 + x + x^2)*(1 - 14*x - 54*x^2 - 81*x^3)). - Colin Barker, Oct 29 2018 EXAMPLE Some solutions for n=4: ..0..1..2....0..1..0....0..1..2....0..1..0....0..1..0....0..1..0....0..1..2 ..1..0..0....1..0..2....1..0..1....2..0..2....1..2..1....2..2..3....2..0..3 ..0..0..0....3..3..0....3..1..3....1..1..3....0..1..3....2..2..0....1..3..1 ..0..0..3....3..3..1....0..2..0....1..1..2....2..3..0....3..0..2....2..1..3 CROSSREFS Column 3 of A240642. Sequence in context: A277832 A221674 A240701 * A245050 A242009 A121137 Adjacent sequences:  A240635 A240636 A240637 * A240639 A240640 A240641 KEYWORD nonn AUTHOR R. H. Hardin, Apr 09 2014 STATUS approved

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Last modified December 6 13:45 EST 2021. Contains 349563 sequences. (Running on oeis4.)