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 A229775 Number of 3 X 3 0..n arrays with rows in lexicographically nondecreasing order and columns in nonincreasing order. 1
 20, 322, 3232, 21331, 103222, 397460, 1287672, 3647349, 9281272, 21642038, 46934680, 95749927, 185397226, 343142248, 610590224, 1049496105, 1749325212, 2836933738, 4488787184, 6946186555, 10534026910, 15683670652, 22960578760 (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) = (1/120)*n^9 + (1/12)*n^8 + (133/360)*n^7 + (371/360)*n^6 + (19/9)*n^5 + (247/72)*n^4 + (403/90)*n^3 + (401/90)*n^2 + (91/30)*n + 1. Conjectures from Colin Barker, Sep 21 2018: (Start) G.f.: x*(20 + 122*x + 912*x^2 + 1101*x^3 + 912*x^4 - 125*x^5 + 118*x^6 - 45*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: ..1..0..0....1..1..0....1..0..0....1..1..1....1..1..0....1..0..0....2..0..0 ..1..2..0....1..1..0....1..2..0....2..1..0....2..1..2....1..3..3....2..0..0 ..3..3..0....3..3..0....3..2..2....3..2..2....2..2..1....3..2..0....3..1..1 CROSSREFS Row 3 of A229774. Sequence in context: A024387 A307173 A101310 * A159648 A353106 A078230 Adjacent sequences: A229772 A229773 A229774 * A229776 A229777 A229778 KEYWORD nonn AUTHOR R. H. Hardin, Sep 29 2013 STATUS approved

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Last modified March 26 05:52 EDT 2023. Contains 361529 sequences. (Running on oeis4.)