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 A209990 #8 Nov 28 2016 03:33:24
%S A209990 0,0,8,64,128,408,472,664,792,984,1272,1592,1720,2104,2296,2872,3128,
%T A209990 3640,3832,4408,4984,5368,5688,6392,6648,7928,8312,8888,9272,10168,
%U A209990 10744,11704,12216,12856,13368,15096,15480,16632,17208,17976
%N A209990 Number of 2 X 2 matrices having all elements in {-n,...n} and determinant 5.
%C A209990 See A210000 for a guide to related sequences.
%H A209990 Chai Wah Wu, <a href="/A209990/b209990.txt">Table of n, a(n) for n = 0..10000</a>
%t A209990 (See the Mathematica section at A209981.)
%Y A209990 Cf. A210000.
%K A209990 nonn
%O A209990 0,3
%A A209990 _Clark Kimberling_, Mar 17 2012