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 A374617 #7 Jul 15 2024 10:20:27
%S A374617 1,1,1,2,6,21,111,710,4968,39879,360952
%N A374617 a(n) is the number of distinct values of the determinant of an n X n symmetric Toeplitz matrix having 1 on the main diagonal and all the integers 1, 2, ..., n-1 off-diagonal.
%H A374617 Wikipedia, <a href="http://en.wikipedia.org/wiki/Toeplitz_matrix">Toeplitz Matrix</a>.
%F A374617 a(n) <= (n-1)! for n > 0.
%t A374617 a[n_]:=CountDistinct[Table[Det[ToeplitzMatrix[Join[{1},Part[Permutations[Range[n-1]], i]]]], {i, (n -1)!}]]; Join[{1}, Array[a, 10]]
%Y A374617 Cf. A000142, A369830.
%Y A374617 Cf. A374239, A374240, A374241, A374242.
%Y A374617 Cf. A374618, A374619, A374620, A374621.
%K A374617 nonn,hard,more
%O A374617 0,4
%A A374617 _Stefano Spezia_, Jul 14 2024