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 A200877 Number of 0..n arrays x(0..8) of 9 elements without any interior element greater than both neighbors or less than both neighbors. 1
 110, 1523, 9858, 42479, 141688, 395929, 971416, 2156867, 4424298, 8509105, 15512938, 27033149, 45322876, 73486107, 115712352, 177555837, 266264422, 391163735, 564102306, 799963779, 1117252576, 1538759685, 2092315544 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Row 7 of A200871. LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = (1/181440)*n^9 + (131/20160)*n^8 + (8893/30240)*n^7 + (4621/1440)*n^6 + (118933/8640)*n^5 + (83957/2880)*n^4 + (763489/22680)*n^3 + (36343/1680)*n^2 + (9169/1260)*n + 1. Conjectures from Colin Barker, Oct 16 2017: (Start) G.f.: x*(110 + 423*x - 422*x^2 - 766*x^3 + 848*x^4 - 246*x^5 + 90*x^6 - 44*x^7 + 10*x^8 - x^9) / (1 - x)^10. a(n) = 10*a(n-1) - 45*a(n-2) + 120*a(n-3) - 210*a(n-4) + 252*a(n-5) - 210*a(n-6) + 120*a(n-7) - 45*a(n-8) + 10*a(n-9) - a(n-10) for n>10. (End) EXAMPLE Some solutions for n=3 ..3....3....3....3....3....0....2....2....3....2....3....3....1....1....2....2 ..0....0....0....1....3....0....2....2....3....3....3....1....2....1....2....0 ..0....0....0....1....3....2....1....0....3....3....3....1....2....1....1....0 ..0....2....1....1....2....2....0....0....2....3....3....1....3....3....1....0 ..3....2....3....1....1....2....0....2....2....3....1....3....3....3....0....0 ..3....1....3....3....1....2....1....2....1....2....1....3....3....2....0....0 ..3....0....3....3....0....2....2....0....1....0....1....3....2....1....0....0 ..2....0....2....2....0....1....3....0....1....0....1....3....2....0....1....0 ..0....1....2....1....2....1....3....2....1....1....3....2....3....0....3....3 CROSSREFS Sequence in context: A248468 A231967 A232339 * A205348 A008450 A163729 Adjacent sequences:  A200874 A200875 A200876 * A200878 A200879 A200880 KEYWORD nonn AUTHOR R. H. Hardin, Nov 23 2011 STATUS approved

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Last modified March 19 00:15 EDT 2019. Contains 321306 sequences. (Running on oeis4.)