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 A210027 #7 Nov 27 2016 21:20:17
%S A210027 0,0,0,3,9,23,27,47,59,79,111,147,159,203,223,291,319,379,399,467,535,
%T A210027 579,615,699,727,883,927,995,1039,1147,1215,1331,1391,1467,1527,1739,
%U A210027 1783,1923,1991,2083,2223,2379,2423,2587,2663,2875,2959,3139
%N A210027 Number of 2 X 2 matrices having all elements in {1,2,...,n} and determinant 5.
%C A210027 See A210000 for a guide to related sequences.
%H A210027 Chai Wah Wu, <a href="/A210027/b210027.txt">Table of n, a(n) for n = 0..10000</a>
%t A210027 (See the Mathematica section at A209978.)
%Y A210027 Cf. A210000.
%K A210027 nonn
%O A210027 0,4
%A A210027 _Clark Kimberling_, Mar 16 2012