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 A135628 #29 Nov 16 2016 06:03:16
%S A135628 0,28,56,84,112,140,168,196,224,252,280,308,336,364,392,420,448,476,
%T A135628 504,532,560,588,616,644,672,700,728,756,784,812,840,868,896,924,952,
%U A135628 980,1008,1036,1064,1092,1120,1148,1176,1204,1232,1260,1288,1316,1344,1372
%N A135628 Multiples of 28.
%H A135628 G. C. Greubel, <a href="/A135628/b135628.txt">Table of n, a(n) for n = 0..1000</a>
%H A135628 Luis Manuel Rivera, <a href="http://arxiv.org/abs/1406.3081">Integer sequences and k-commuting permutations</a>, arXiv preprint arXiv:1406.3081 [math.CO], 2014.
%H A135628 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1)
%F A135628 a(n) = 28*n.
%F A135628 From _G. C. Greubel_, Oct 24 2016: (Start)
%F A135628 G.f.: (28*x)/(1 - x)^2.
%F A135628 E.g.f.: 28*x*exp(x).
%F A135628 a(n) = 2*a(n-1) - a(n-2). (End)
%e A135628 a(9) = 28*9 = 252.
%t A135628 Range[0, 3000, 28] (* _Vladimir Joseph Stephan Orlovsky_, Jun 03 2011 *)
%t A135628 LinearRecurrence[{2,-1},{0,28},25] (* _G. C. Greubel_, Oct 24 2016 *)
%Y A135628 Cf. A008588, A008596, A127777.
%K A135628 easy,nonn
%O A135628 0,2
%A A135628 _Omar E. Pol_, Nov 25 2007