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 A089036 #12 Jul 09 2018 02:45:58
%S A089036 1,12,729,758160,2972290464,354396766517640,92079975413927255040,
%T A089036 939180873931369976460153600,22528399544939174411840147874772641,
%U A089036 11276516942788127325350557035641264267894784,25780902234356363794160964471948503247074139517747200
%N A089036 Number of n X n matrices over GF(3) with characteristic polynomial x^n - 1.
%H A089036 I. Reiner, <a href="https://projecteuclid.org/euclid.ijm/1255629830">On the number of matrices with given characteristic polynomial</a>, Illinois J. Math. 5 1961 324-329.
%o A089036 (PARI) \\ see Reiner reference.
%o A089036 F(u,r)={prod(i=1, r, (1-u^(-i)))}
%o A089036 a(n, q=3)={my(D=ffgen(q)); my(f=factor(D^0*(x^n-1))); q^(n^2-n)*F(q,n)/prod(i=1, #f~, F(q^poldegree(f[i,1]), f[i,2]))} \\ _Andrew Howroyd_, Jul 08 2018
%Y A089036 Cf. A088654, A089035, A089037.
%K A089036 nonn
%O A089036 1,2
%A A089036 Yuval Dekel (dekelyuval(AT)hotmail.com) and _W. Edwin Clark_, Nov 29 2003
%E A089036 Offset corrected and a(9)-a(11) from _Andrew Howroyd_, Jul 08 2018