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 A220791 #11 Jun 06 2025 19:07:17
%S A220791 1,12,26208,9726417792,610296923230525440,
%T A220791 6471875909051511775903457280,
%U A220791 11598637276362103019770723830073032376320,3512938445418644176053176560741858449740612202579886080
%N A220791 Number of nonsingular n X n matrices over GF(13).
%H A220791 Vincenzo Librandi, <a href="/A220791/b220791.txt">Table of n, a(n) for n = 0..30</a>
%H A220791 J. Overbey, W. Traves and J. Wojdylo, <a href="http://jeff.over.bz/papers/undergrad/on-the-keyspace-of-the-hill-cipher.pdf">On the Keyspace of the Hill Cipher</a>.
%t A220791 Table[Product[13^n - 13^k, {k, 0, n-1}], {n, 0, 8}]
%o A220791 (Magma) [1] cat [&*[(13^n - 13^k): k in [0..n-1]]: n in [1..8]];
%Y A220791 Cf. A002884, A003787, A003789, A003790, A053290-A053293.
%K A220791 nonn
%O A220791 0,2
%A A220791 _Vincenzo Librandi_, Jan 29 2013