This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A327273 #11 Nov 28 2019 07:54:11 %S A327273 1,5,105,425,144925,580125,243697125,46420625,253459513125 %N A327273 An upper bound sequence for A327272. %C A327273 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. %H A327273 Chris Pinner and Chris Smyth, <a href="https://www.maths.ed.ac.uk/~chris/papers/MinimalLattices040919.pdf">Lattices of minimal index in Z^n having an orthogonal basis containing a given basis vector</a> %H A327273 Christopher J. Smyth, <a href="/A327273/a327273.pdf">List of n, a(n) and associated matrix for 0 <= n <= 8</a> %e A327273 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. %K A327273 nonn,more %O A327273 0,2 %A A327273 _Christopher J. Smyth_, Sep 09 2019