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 A238518 Number of (n+1) X (1+1) 0..3 arrays with no element equal to all horizontal neighbors or equal to all vertical neighbors. 1
 84, 588, 7056, 74676, 812028, 8777664, 95006100, 1028017452, 11124397872, 120377861940, 1302620868444, 14095781346528, 152531780288916, 1650560738719116, 17860873095687888, 193274188450247604 (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) = 9*a(n-1) + 21*a(n-2) - 14*a(n-3). Empirical g.f.: 84*x*(1 - 2*x) / (1 - 9*x - 21*x^2 + 14*x^3). - Colin Barker, Oct 24 2018 EXAMPLE Some solutions for n=4: ..3..1....1..2....2..1....3..2....3..1....2..0....2..3....2..3....3..0....0..3 ..2..3....0..1....0..3....1..0....1..3....3..2....3..2....1..0....1..3....2..0 ..0..3....0..3....2..3....3..1....3..0....0..3....1..2....2..0....2..1....1..3 ..0..2....1..0....1..2....1..3....1..0....3..2....0..1....1..2....3..0....2..0 ..1..0....0..1....3..0....2..0....3..2....2..3....2..3....3..1....0..3....1..3 CROSSREFS Column 1 of A238523. Sequence in context: A008429 A175813 A238523 * A264654 A230907 A220016 Adjacent sequences:  A238515 A238516 A238517 * A238519 A238520 A238521 KEYWORD nonn AUTHOR R. H. Hardin, Feb 28 2014 STATUS approved

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Last modified December 1 22:12 EST 2021. Contains 349435 sequences. (Running on oeis4.)