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 A301371 Maximum determinant of an n X n matrix with n copies of the numbers 1 .. n. 18
 1, 1, 3, 18, 160, 2325, 41895, 961772, 27296640, 933251220 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS 929587995 <= a(9) <= 934173632 (upper bound from Gasper's determinant theorem). The lower bound corresponds to a Latin square provided in A309985, but it is unknown whether a larger determinant value can be achieved by an unconstrained arrangement of the matrix entries. - Hugo Pfoertner, Aug 27 2019 Oleg Vlasii found a 9 X 9 matrix significantly exceeding the determinant value achievable by a Latin square. See example and links. - Hugo Pfoertner, Nov 04 2020 LINKS Ortwin Gasper, Hugo Pfoertner and Markus Sigg, An Upper Bound for the Determinant of a Matrix with given Entry Sum and Square Sum, JIPAM, Journal of Inequalities in Pure and Applied Mathematics, Volume 10, Issue 3, Article 63, 2008. IBM Research, Large 9x9 determinant, Ponder This Challenge November 2019. Markus Sigg, Gasper's determinant theorem, revisited, arXiv:1804.02897 [math.CO], 2018. Oleg Vlasii, Determinant-OEIS-A301371-9, program and description, 4 Dec 2019. FORMULA A328030(n) <= a(n) <= A328031(n). - Hugo Pfoertner, Nov 04 2019 EXAMPLE Matrices with maximum determinants: a(2) = 3: (2 1) (1 2) a(3) = 18: (3 1 2) (2 3 1) (1 2 3) a(4) = 160: (4 3 2 1) (1 4 3 2) (3 1 4 3) (2 2 1 4) a(5) = 2325: (5 3 1 2 4) (2 5 4 1 3) (4 1 5 3 2) (3 4 2 5 1) (1 2 3 4 5) a(6) = 41895: (6 1 4 2 3 5) (3 6 2 1 5 4) (4 5 6 3 2 1) (5 3 1 6 4 2) (1 2 5 4 6 3) (2 4 3 5 1 6) a(7) = 961772: (7 2 3 5 1 4 6) (3 7 6 4 2 1 5) (2 1 7 6 4 5 3) (4 5 1 7 6 3 2) (6 3 5 1 7 2 4) (5 6 4 2 3 7 1) (1 4 2 3 5 6 7) a(8) = 27296640: (8 8 3 5 4 3 4 1) (1 8 6 3 1 6 6 5) (5 3 8 1 7 6 4 2) (5 1 6 8 2 4 7 3) (1 5 2 7 8 6 4 3) (7 3 2 4 3 8 2 7) (5 4 2 2 6 2 8 7) (4 5 7 6 5 1 1 7) a(n) is an upper bound for the determinant of an n X n Latin square. a(n) = A309985(n) for n <= 7. a(8) > A309985(8). - Hugo Pfoertner, Aug 26 2019 From Hugo Pfoertner, 2020 Nov 04: (Start) a(9) = 933251220, achieved by a Non-Latin square: (9 5 5 3 3 2 2 8 8) (4 9 2 6 7 5 3 1 8) (4 7 9 2 1 8 6 3 5) (6 3 7 9 4 1 8 2 5) (6 2 8 5 9 7 1 4 3) (7 4 1 8 2 9 5 6 3) (7 6 3 1 8 4 9 5 2) (1 8 6 7 5 3 4 9 2) (1 1 4 4 6 6 7 7 9) found by Oleg Vlasii as an answer to the IBM Ponder This Challenge November 2019. See links. (End) CROSSREFS Cf. A085000, A309985, A328030, A328031. Sequence in context: A052182 A309985 A328030 * A115415 A065058 A032031 Adjacent sequences: A301368 A301369 A301370 * A301372 A301373 A301374 KEYWORD nonn,hard,more AUTHOR Hugo Pfoertner, Mar 21 2018 EXTENSIONS a(8) from Hugo Pfoertner, Aug 26 2019 a(9) from Hugo Pfoertner, Nov 04 2020 STATUS approved

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