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 A153171 #11 Jun 13 2015 00:52:45
%S A153171 6,6,-6,24,12,-24,54,18,-54,96,24,-96,150,30,-150,216,36,-216,294,42,
%T A153171 -294,384,48,-384,486,54,-486,600,60,-600,726,66,-726,864,72,-864,
%U A153171 1014,78,-1014,1176,84,-1176,1350,90,-1350,1536,96,-1536,1734,102,-1734
%N A153171 First differences of A046163.
%H A153171 Colin Barker, <a href="/A153171/b153171.txt">Table of n, a(n) for n = 0..1000</a>
%H A153171 <a href="/index/Rec#order_08">Index entries for linear recurrences with constant coefficients</a>, signature (-1,-1,2,2,2,-1,-1,-1).
%F A153171 G.f.: 6*(x^4+2*x^3+x^2+2*x+1) / ((x-1)^2*(x^2+x+1)^3). - _Colin Barker_, Nov 04 2014
%t A153171 Differences[Table[Denominator[(n-1)^2/(n^2+n+1)],{n,1,50}]] (* _Vaclav Kotesovec_, Nov 04 2014 *)
%o A153171 (PARI) Vec(6*(x^4+2*x^3+x^2+2*x+1)/((x-1)^2*(x^2+x+1)^3) + O(x^100)) \\ _Colin Barker_, Nov 04 2014
%Y A153171 Cf. A046163.
%K A153171 sign,easy
%O A153171 0,1
%A A153171 _Paul Curtz_, Dec 20 2008
%E A153171 Edited by _N. J. A. Sloane_, Dec 20 2008
%E A153171 More terms from _Colin Barker_, Nov 04 2014