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 A385034 #34 Jun 25 2025 06:39:37 %S A385034 1,1,3,27,189,1701,46656,606528,8957952,387420489,7360989291, %T A385034 154580775111,8916100448256,222902511206400 %N A385034 Absolute value squared of the maximal determinant of a matrix of order n with entries in the third roots of unity. %C A385034 The n-th term is equal to n^n if and only if a Butson-type Hadamard matrix over the third roots exist. %H A385034 G. Nuñez Ponasso, <a href="https://doi.org/10.1016/j.laa.2025.05.024">Maximal determinants of matrices over the roots of unity</a>, Linear Algebra and its Applications, 723 (2025), 201-243. %e A385034 With w=exp(2*Pi*i/3) and i the imaginary unit, a matrix corresponding to a(3) = 27 is %e A385034 [1, 1, 1; %e A385034 1, w, w^2; %e A385034 1, w^2, w], %e A385034 and a matrix corresponding to a(4) = 189 is %e A385034 [w, 1, 1, 1; %e A385034 1, w, 1, 1; %e A385034 1, 1, w, 1; %e A385034 1, 1, 1, w]. %Y A385034 Cf. A000312, A003433. %K A385034 nonn,hard,more %O A385034 0,3 %A A385034 _Guillermo N. Ponasso_, Jun 16 2025