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 A018842 #45 Apr 07 2021 14:39:51
%S A018842 1,8,32,68,96,120,148,176,204,232,260,288,316,344,372,400,428,456,484,
%T A018842 512,540,568,596,624,652,680,708,736,764,792,820,848,876,904,932,960,
%U A018842 988,1016,1044,1072,1100,1128,1156
%N A018842 Number of squares on infinite chessboard at n knight's moves from center.
%H A018842 Moon Duchin, <a href="https://www.ams.org/journals/notices/201608/rnoti-p871.pdf">Counting in Groups: Fine Asymptotic Geometry</a>, Notices of the AMS 63.8 (2016), pp. 871-974. See p. 873.
%H A018842 Mordechai Katzman, <a href="http://www.katzman.staff.shef.ac.uk/ComputerAlgebra/knight.ps">Knight's moves on an infinite board</a>
%H A018842 M. Katzman, <a href="http://dx.doi.org/10.1007/s108-01-005-4531-6">Counting Monomials</a>, J. Alg. Comb. 22 (2005) 331-341.
%H A018842 A. M. Miller and D. L. Farnsworth, <a href="http://dx.doi.org/10.4236/ojdm.2013.33027">Counting the Number of Squares Reachable in k Knight's Moves</a>, Open Journal of Discrete Mathematics, 2013, 3, 151-154.
%H A018842 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1).
%F A018842 a(n) = 28*n-20, n >= 5.
%F A018842 G.f.: (1 + 5*x + 12*x^2 - 8*x^4 + 4*x^5)*(1+x)/(1-x)^2.
%p A018842 (1 + 5*x + 12*x^2 - 8*x^4 + 4*x^5)*(1+x)/(1-x)^2; seq(coeff(series(%, x, n+1), x, n), n=0..50);
%t A018842 CoefficientList[Series[(1+5x+12x^2-8x^4+4x^5)(1+x)/(1-x)^2, {x,0,50}], x] (* or *) Join[{1,8,32,68,96},LinearRecurrence[{2,-1},{120,148},46]] (* _Harvey P. Dale_, Jul 05 2011 *)
%Y A018842 Cf. A018836 (partial sums), A038522.
%K A018842 nonn,nice,walk,easy
%O A018842 0,2
%A A018842 _N. J. A. Sloane_, _Marc LeBrun_
%E A018842 Formula corrected by _Jean Drabbe_, Mar 11 2013