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 A224257 Number of n X 3 0..2 arrays with rows and antidiagonals unimodal and columns nondecreasing. 1
 22, 158, 648, 2017, 5246, 11990, 24842, 47643, 85838, 146878, 240668, 380061, 581398, 865094, 1256270, 1785431, 2489190, 3411038, 4602160, 6122297, 8040654, 10436854, 13401938, 17039411, 21466334, 26814462, 33231428, 40881973, 49949222 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Column 3 of A224262. LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = (23/360)*n^6 + (19/40)*n^5 + (211/72)*n^4 + (119/24)*n^3 + (2161/180)*n^2 + (77/30)*n - 1. Conjectures from Colin Barker, Aug 29 2018: (Start) G.f.: x*(22 + 4*x + 4*x^2 + 29*x^3 - 25*x^4 + 13*x^5 - x^6) / (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>7. (End) EXAMPLE Some solutions for n=3: ..0..1..0....0..0..1....0..1..1....2..2..0....0..0..0....1..2..0....0..0..0 ..2..1..0....0..1..1....2..2..2....2..2..0....2..1..1....2..2..1....0..0..0 ..2..1..1....1..1..2....2..2..2....2..2..2....2..2..1....2..2..2....2..2..0 CROSSREFS Cf. A224262. Sequence in context: A130438 A041934 A027943 * A244868 A223913 A189416 Adjacent sequences:  A224254 A224255 A224256 * A224258 A224259 A224260 KEYWORD nonn AUTHOR R. H. Hardin, Apr 02 2013 STATUS approved

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Last modified October 18 12:18 EDT 2019. Contains 328160 sequences. (Running on oeis4.)