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 A207924 Number of n X 4 0..1 arrays avoiding 0 0 0 and 0 1 0 horizontally and 0 0 0 and 1 1 1 vertically. 2
 9, 81, 144, 576, 1936, 6400, 21904, 73984, 250000, 846400, 2862864, 9684544, 32764176, 110838784, 374964496, 1268499456, 4291298064, 14517358144, 49111878544, 166144281664, 562062085264, 1901442429184, 6432533627536 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Column 4 of A207928. It seems that all terms are squares. - Colin Barker, Mar 06 2018 LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 2*a(n-1) + 3*a(n-2) + 6*a(n-3) - a(n-4) - a(n-6) for n>8. Empirical g.f.: x*(9 + 63*x - 45*x^2 - 9*x^3 - 125*x^4 + 17*x^5 - 7*x^6 + 17*x^7) / ((1 + x + x^2 - x^3)*(1 - 3*x - x^2 - x^3)). - Colin Barker, Mar 06 2018 EXAMPLE Some solutions for n=8: ..0..1..1..0....1..0..0..1....1..0..0..1....1..0..1..1....0..1..1..0 ..1..0..0..1....0..1..1..0....0..1..1..0....0..0..1..1....0..1..1..1 ..1..1..1..1....1..0..1..1....0..0..1..1....1..1..0..0....1..0..0..1 ..0..1..1..0....1..1..0..1....1..0..0..1....1..0..1..1....0..1..1..0 ..1..0..0..1....0..1..1..0....1..1..0..0....0..0..1..1....0..1..1..1 ..1..0..1..1....0..0..1..1....0..1..1..0....1..1..0..0....1..0..0..1 ..0..1..1..0....1..1..0..1....0..0..1..1....1..0..1..1....1..1..1..0 ..1..1..0..1....1..1..1..0....1..0..0..1....0..1..1..1....0..1..1..1 CROSSREFS Cf. A207928. Sequence in context: A207695 A158028 A207591 * A043180 A207875 A207678 Adjacent sequences:  A207921 A207922 A207923 * A207925 A207926 A207927 KEYWORD nonn AUTHOR R. H. Hardin, Feb 21 2012 STATUS approved

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Last modified December 13 09:57 EST 2019. Contains 329968 sequences. (Running on oeis4.)