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 A368539 Maximal sum of elements of A^2 where A is a square matrix of size n whose elements are a permutation of {1, 2, ..., n^2}. 2
 1, 54, 761, 5284 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS The next terms are at least (and probably equal to) 5284, 24303, 85352 and 248045. The lower bounds for the terms a(4)-a(7) are confirmed. a(8) >= 626610, a(9) >= 1421271, a(10) >= 2959798, a(11) >= 5750977. - Hugo Pfoertner, Jan 21 2024 In addition to the conditions (a)-(d) described in para 2.2 of Fried and Mansour (2023), conjecturally optimal matrices found using simulated annealing have the following additional property: If, using simultaneous row and column rearrangement, the matrix is brought into a form in which the terms of the main diagonal are sorted in ascending order, then every single row and every single column is monotonically increasing. See the linked file for examples from n=2 to n=14. - Hugo Pfoertner, Jan 25 2024 LINKS Table of n, a(n) for n=1..4. Sela Fried and Toufik Mansour, On the maximal sum of the entries of a matrix power, arXiv:2308.00348 [math.CO], 2023. Hugo Pfoertner, Examples of solutions found by simulated annealing, for n=2-14. Jan 25, 2024. EXAMPLE [1 3 4] For n = 3, the sum of the elements of A^2, where A = [2 6 8], is 761. [5 7 9] CROSSREFS Cf. A085000, A350566, A369396. Sequence in context: A288838 A157094 A232829 * A093972 A281775 A344272 Adjacent sequences: A368536 A368537 A368538 * A368540 A368541 A368542 KEYWORD nonn,hard,more AUTHOR Sela Fried, Dec 29 2023 STATUS approved

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Last modified May 27 01:15 EDT 2024. Contains 372847 sequences. (Running on oeis4.)