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 A022975 #19 Jul 29 2024 03:46:53
%S A022975 19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,0,-1,-2,-3,-4,-5,-6,
%T A022975 -7,-8,-9,-10,-11,-12,-13,-14,-15,-16,-17,-18,-19,-20,-21,-22,-23,-24,
%U A022975 -25,-26,-27,-28,-29,-30,-31,-32,-33,-34,-35,-36,-37,-38,-39,-40,-41
%N A022975 a(n) = 19 - n.
%H A022975 Vincenzo Librandi, <a href="/A022975/b022975.txt">Table of n, a(n) for n = 0..1000</a>
%H A022975 Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/RecursiveSequences.html">Recursive Sequences</a>.
%H A022975 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1).
%F A022975 From _Chai Wah Wu_, Jun 17 2016: (Start)
%F A022975 a(n) = 2*a(n-1) - a(n-2) for n > 1.
%F A022975 G.f.: (-20*x + 19)/(x - 1)^2. (End)
%t A022975 CoefficientList[Series[(-20 x + 19) /(x - 1)^2, {x, 0, 100}], x] (* _Vincenzo Librandi_, Jun 18 2016 *)
%t A022975 19-Range[0,80] (* _Harvey P. Dale_, Aug 23 2017 *)
%o A022975 (Magma) [19-n: n in [0..70]]; // _Vincenzo Librandi_, Jun 18 2016
%Y A022975 Cf. A022958 - A022995.
%K A022975 sign
%O A022975 0,1
%A A022975 _N. J. A. Sloane_