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 A346019 #21 Jul 05 2021 00:03:59
%S A346019 1,2,48,2688,1935360,1919877120,23222833643520,335564785519165440,
%T A346019 65717007596073359769600,21492090164219831579049984000,
%U A346019 66041307304745851496871108594892800,226523509196861965428709270554756199219200,16622838761287803491875715175557341313583022080000
%N A346019 Number of n X n invertible matrices over GF(2) that have order 2^n-1.
%C A346019 Equivalently, a(n) is the number of n X n matrices over GF(2) whose characteristic polynomial is primitive.
%C A346019 2^n - 1 is the greatest order that a matrix in the general linear group GL_n(F_2) can have.
%H A346019 M. R. Darafsheh, <a href="https://doi.org/10.1016/j.ffa.2004.12.003">Order of elements in the groups related to the general linear group</a>, Finite fields and their applications, 11 (2005), 738-747.
%F A346019 a(n) = A011260(n) * A002884(n)/A000225(n).
%p A346019 a:= n-> mul(2^n-2^i, i=0..n-1)*numtheory[phi](2^n-1)/((2^n-1)*n):
%p A346019 seq(a(n), n=1..14); # _Alois P. Heinz_, Jul 01 2021
%t A346019 nn = 13; Table[EulerPhi[2^n - 1]/n, {n, 1, nn}]* Table[Product[2^n - 2^i, {i, 0, n - 1}], {n, 1, nn}]/Table[2^n - 1, {n, 1, nn}]
%Y A346019 Cf. A000010, A011260, A002884, A000225, A345463.
%K A346019 nonn
%O A346019 1,2
%A A346019 _Geoffrey Critzer_, Jul 01 2021