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 A115221 #3 Mar 30 2012 17:22:41
%S A115221 1,344,8451,100864,465125,2907144,6569479,27557888,59895369,160003000,
%T A115221 233671691,852401664,878081581,2259900776,3930771375
%N A115221 Number of 3 X 3 matrices over Z(n) having determinant 0.
%F A115221 a(n)=n^9-A115222(n). For prime n, a(n)=n^3 (n^5+n^4-n^2-n+1)
%t A115221 Table[cnt=0; Do[m={{a, b, c}, {d, e, f}, {g, h, i}}; If[Det[m, Modulus->n]==0, cnt++ ], {a, 0, n-1}, {b, 0, n-1}, {c, 0, n-1}, {d, 0, n-1}, {e, 0, n-1}, {f, 0, n-1}, {g, 0, n-1}, {h, 0, n-1}, {i, 0, n-1}]; cnt, {n, 2, 7}]
%K A115221 mult,nonn
%O A115221 1,2
%A A115221 _T. D. Noe_, Jan 16 2006