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 A053293 #32 Jul 06 2025 02:54:30
%S A053293 1,6,2016,33784128,27811094169600,1122211189922928537600,
%T A053293 2218959336124989671614429593600,
%U A053293 214992513152176999576908105619651923148800,1020690003311610463765638355505358381593396977336320000,237443634207909205360438080389756681126654524500073656592021585920000
%N A053293 Number of nonsingular n X n matrices over GF(7).
%H A053293 Vincenzo Librandi, <a href="/A053293/b053293.txt">Table of n, a(n) for n = 0..30</a>
%H A053293 Jeffrey Overbey, William Traves, and Jerzy Wojdylo, <a href="https://doi.org/10.1080/0161-110591893771">On the Keyspace of the Hill Cipher</a>, Cryptologia, Vol. 29, Iss. 1 (2005), pp. 59-72; <a href="http://jeff.over.bz/papers/undergrad/on-the-keyspace-of-the-hill-cipher.pdf">author's copy</a>.
%F A053293 a(n) = (7^n - 1)*(7^n - 7)*...*(7^n - 7^(n-1)).
%F A053293 a(n) = A109493(n)*A027875(n). - _Bruno Berselli_, Jan 30 2013
%F A053293 a(n) ~ c * 7^(n^2), where c = A132035. - _Amiram Eldar_, Jul 06 2025
%t A053293 Table[Product[7^n - 7^k, {k, 0, n-1}], {n, 0, 10}] (* _Vincenzo Librandi_, Jan 28 2013 *)
%o A053293 (Magma) [1] cat [&*[(7^n - 7^k): k in [0..n-1]]: n in [1..7]]; // _Bruno Berselli_, Jan 28 2013
%o A053293 (PARI) for(n=0,10, print1(prod(k=0,n-1, 7^n - 7^k), ", ")) \\ _G. C. Greubel_, May 31 2018
%Y A053293 Column k=7 of A316622.
%Y A053293 Cf. A002884, A003790, A027875, A053290, A053291, A053292, A109493, A132035.
%K A053293 nonn,easy
%O A053293 0,2
%A A053293 _Stephen G Penrice_, Mar 04 2000
%E A053293 More terms from _Vladeta Jovovic_, Mar 16 2000