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 A112261 #16 Sep 21 2020 07:06:23 %S A112261 -2,0,12,20,-12,-60,52,420,468,-700,-1548,3300,13588,8580,-29388, %T A112261 -30940,152148,406980,60532,-1043100,-236652,6032900,11173812, %U A112261 -4569180,-32487212,19343940,216401652,273243620,-323927532,-880031100,1489420852,7157028900 %N A112261 a(n) = A112260(n+1) - A112260(n). %H A112261 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-6,8). %F A112261 a(n) = 3*a(n-1)-6*a(n-2)+8*a(n-3); G.f.: -2*(3*x-1) / ((2*x-1)*(4*x^2-x+1)). - _Colin Barker_, Nov 02 2014 %e A112261 a(4) = A112260(5) - A112260(4) = 31-11 = 20. %Y A112261 Cf. A112259, A112260. %K A112261 sign %O A112261 1,1 %A A112261 _Russell Walsmith_, Aug 30 2005 %E A112261 Name corrected and more terms from _Colin Barker_, Nov 02 2014