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 A364229 #9 Aug 02 2023 14:42:27
%S A364229 1,2,5,24,120,719,5040,40317,362874,3628798
%N A364229 a(n) is the number of n X n nonsingular Hermitian Toeplitz matrices using all the integers 1, 2, ..., n and with all off-diagonal elements purely imaginary.
%H A364229 Wikipedia, <a href="https://en.wikipedia.org/wiki/Toeplitz_matrix">Toeplitz Matrix</a>
%t A364229 a[n_]:=Count[Flatten[Table[MatrixRank[ToeplitzMatrix[Join[{d}, I Part[Permutations[Drop[Range[n], {d}]], i]]]],{i,(n-1)!},{d,n}]],n]; Array[a,9]
%Y A364229 Right diagonal of A364228.
%Y A364229 Cf. A359614 (minimal determinant), A359615 (maximal determinant), A359616 (minimal permanent), A359617 (maximal permanent).
%K A364229 nonn,hard,more
%O A364229 1,2
%A A364229 _Stefano Spezia_, Jul 14 2023