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 A327273 An upper bound sequence for A327272. 2
 1, 5, 105, 425, 144925, 580125, 243697125, 46420625, 253459513125 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS a(n) can be calculated by a faster algorithm than that for A327272(n). It gives a small (but not necessarily smallest) positive determinant with top row [1,2,2^2,...,2^n] and all entries integers, and rows orthogonal. Note that a(n) = A327272(n) for n=0,1 and 3. See Pinner and Smyth link below for both algorithms, and more details of the sequences. 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 0 <= n <= 8 EXAMPLE a(2) = 105 since the algorithm for a(n) produces the determinant([[1,2,4],[2,-1,0],[4,8,-5]]) = 105, having top row [1,2,2^2] and all rows orthogonal. CROSSREFS Sequence in context: A057016 A193340 A083252 * A034225 A273966 A114481 Adjacent sequences:  A327270 A327271 A327272 * A327274 A327275 A327276 KEYWORD nonn,more AUTHOR Christopher J. Smyth, Sep 09 2019 STATUS approved

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Last modified February 25 21:51 EST 2020. Contains 332260 sequences. (Running on oeis4.)