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 A060641 #25 Aug 13 2020 14:01:06
%S A060641 161,257,373,509,665,841,1037,1253,1489,1745,2021,2317,2633,2969,3325,
%T A060641 3701,4097,4513,4949,5405,5881,6377,6893,7429,7985,8561,9157,9773,
%U A060641 10409,11065,11741,12437,13153,13889,14645,15421,16217,17033
%N A060641 Surround numbers of a length 2n zig-zag.
%H A060641 Harry J. Smith, <a href="/A060641/b060641.txt">Table of n, a(n) for n = 2..1000</a>
%H A060641 E. J. Friedman, <a href="https://erich-friedman.github.io/mathmagic/0599.html">Math. Magic</a>
%H A060641 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3, -3, 1).
%F A060641 a(n) = 10n^2 + 46n + 29 with n > 1.
%F A060641 From _Colin Barker_, Apr 22 2012: (Start)
%F A060641 a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3).
%F A060641 G.f.: x^2*(161 - 226*x + 85*x^2)/(1-x)^3. (End)
%t A060641 LinearRecurrence[{3,-3,1},{161,257,373},40] (* or *) Table[10x^2+66x+85,{x,40}] (* _Harvey P. Dale_, May 26 2013 *)
%o A060641 (PARI) a(n)={10*n^2 + 46*n + 29} \\ _Harry J. Smith_, Jul 09 2009
%Y A060641 Cf. A047875, A000105, A060633.
%K A060641 nonn,easy
%O A060641 2,1
%A A060641 _Jason Earls_, Apr 16 2001