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 A251130 Number of (n+1) X (1+1) 0..2 arrays with no 2 X 2 subblock having the sum of its diagonal elements greater than the maximum of its antidiagonal elements. 1
 40, 133, 369, 919, 2129, 4699, 10033, 20947, 43077, 87703, 177389, 357271, 717625, 1439011, 2882553, 5770507, 11547389, 23102239, 46213141, 92436271, 184883985, 369781003, 739576769, 1479170179, 2958359029, 5916738919, 11833501053 (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) = 5*a(n-1) - 8*a(n-2) + 2*a(n-3) + 7*a(n-4) - 7*a(n-5) + 2*a(n-6). Conjectures from Colin Barker, Nov 26 2018: (Start) G.f.: x*(40 - 67*x + 24*x^2 + 58*x^3 - 60*x^4 + 17*x^5) / ((1 - x)^4*(1 + x)*(1 - 2*x)). a(n) = (-957 + (-1)^n + 529*2^(1+n) - 540*n - 126*n^2 - 12*n^3) / 12. (End) EXAMPLE Some solutions for n=4: ..0..2....0..2....0..0....0..2....0..2....0..2....1..1....0..2....1..2....0..1 ..0..2....1..2....2..2....1..2....0..2....1..1....0..0....1..2....0..0....0..0 ..0..0....0..0....0..0....0..1....0..0....0..0....1..1....0..1....1..1....0..0 ..1..1....1..1....0..0....2..2....2..2....2..2....1..0....1..0....0..0....2..2 ..0..0....2..1....2..2....2..0....0..0....2..0....2..0....2..1....0..0....2..0 CROSSREFS Column 1 of A251137. Sequence in context: A300536 A260536 A251137 * A231077 A044372 A044753 Adjacent sequences: A251127 A251128 A251129 * A251131 A251132 A251133 KEYWORD nonn AUTHOR R. H. Hardin, Nov 30 2014 STATUS approved

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Last modified July 13 07:46 EDT 2024. Contains 374274 sequences. (Running on oeis4.)