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 A327271 Smallest modulus of any n X n integer determinant whose top row has all 1's and whose rows are pairwise orthogonal. 4
 1, 2, 6, 8, 40, 48, 336, 128, 864, 1280, 8448, 3072, 39936 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(n) = A327267(2^n), since 2^n = (p_1)^n is the Heinz code for the multiset {1,1,...,1}. See Pinner and Smyth link below for more details, including an algorithm for computing A327267(n). Also, see file link below for {(n, a(n), matrix(n)), n <= 13}, where matrix(n) has minimal modulus determinant equal to a(n) among n X n matrices with top row all 1's and all rows orthogonal. For the first 13 terms, the number of prime factors counted with multiplicity equals n-1: A001222(a(n))=n-1. How far does this hold? - Jon Maiga, Sep 07 2019 LINKS Chris Pinner and Chris Smyth, Lattices of minimal index in Z^n having an orthogonal basis containing a given basis vector Christopher J. Smyth, List of n, a(n) and associated matrix for n up to 13 EXAMPLE a(3) = 6 because the matrix [[1,1,1],[1,-1,0],[1,1,-2]] has top row of 3 1's and all rows orthogonal, and minimal positive determinant equal to 6. CROSSREFS Subsequence of A327267, see comments; A327273 is similar, but determinant's top row is 1,2,2^2,...,2^{n-1}. Sequence in context: A235320 A152158 A291782 * A335111 A095239 A192009 Adjacent sequences:  A327268 A327269 A327270 * A327272 A327273 A327274 KEYWORD nonn,more AUTHOR Christopher J. Smyth, Sep 02 2019 STATUS approved

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Last modified August 10 14:50 EDT 2020. Contains 336381 sequences. (Running on oeis4.)