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 A181192 Number of n X 5 matrices containing a permutation of 1..n*5 in increasing order rowwise, columnwise, diagonally and (downwards) antidiagonally. 2
 1, 14, 290, 6392, 141696, 3142704, 69705920, 1546100352, 34293030016, 760631058944, 16871055411200, 374205743270912, 8300010573582336, 184097055591849984, 4083335265314938880, 90569764059295875072 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Column 5 of A181196. LINKS R. H. Hardin, Table of n, a(n) for n=1..100 FORMULA Empirical: a(n) = 24*a(n-1) - 40*a(n-2) - 8*a(n-3). Conjectures from Colin Barker, Feb 27 2018: (Start) G.f.: x*(1 - 10*x - 6*x^2) / ((1 - 2*x)*(1 - 22*x - 4*x^2)). a(n) = 2^(n-2) + ((11-5*sqrt(5))^n*(2+sqrt(5)) + (-2+sqrt(5))*(11+5*sqrt(5))^n) / (4*sqrt(5)). (End) EXAMPLE Some solutions for 4 X 5: ..1..2..3..4..5....1..2..3..4..5....1..2..3..4..5....1..2..3..4..5 ..6..7..8..9.10....6..7..8..9.10....6..7..8..9.10....6..7..8..9.10 .11.12.13.14.15...11.12.13.14.17...11.12.13.14.16...11.12.13.14.18 .16.17.18.19.20...15.16.18.19.20...15.17.18.19.20...15.16.17.19.20 CROSSREFS Cf. A181196. Sequence in context: A027401 A259432 A233069 * A227580 A215869 A262740 Adjacent sequences: A181189 A181190 A181191 * A181193 A181194 A181195 KEYWORD nonn AUTHOR R. H. Hardin, Oct 10 2010 STATUS approved

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Last modified August 7 08:03 EDT 2024. Contains 375008 sequences. (Running on oeis4.)