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 A224159 Number of 3 X n 0..1 arrays with diagonals and rows unimodal and antidiagonals nondecreasing. 1
 8, 36, 89, 187, 373, 702, 1252, 2130, 3479, 5486, 8391, 12497, 18181, 25906, 36234, 49840, 67527, 90242, 119093, 155367, 200549, 256342, 324688, 407790, 508135, 628518, 772067, 942269, 1142997, 1378538, 1653622, 1973452, 2343735, 2770714 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Row 3 of A224158. LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = (1/720)*n^6 + (1/240)*n^5 + (47/144)*n^4 - (3/16)*n^3 + (1111/180)*n^2 - (199/60)*n + 20 for n>2. Conjectures from Colin Barker, Aug 28 2018: (Start) G.f.: x*(8 - 20*x + 5*x^2 + 40*x^3 - 47*x^4 - 5*x^5 + 41*x^6 - 27*x^7 + 6*x^8) / (1 - x)^7. a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7) for n>9. (End) EXAMPLE Some solutions for n=3: ..0..0..1....0..0..1....0..0..0....0..1..0....1..0..0....0..1..1....1..1..0 ..1..1..0....1..1..0....0..0..0....1..0..0....0..1..0....1..1..1....1..0..0 ..1..1..1....1..1..0....1..0..0....0..1..0....1..0..0....1..1..0....1..1..0 CROSSREFS Cf. A224158. Sequence in context: A321778 A009923 A187287 * A321251 A035006 A245360 Adjacent sequences: A224156 A224157 A224158 * A224160 A224161 A224162 KEYWORD nonn AUTHOR R. H. Hardin, Mar 31 2013 STATUS approved

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Last modified September 8 06:47 EDT 2024. Contains 375751 sequences. (Running on oeis4.)