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 A211703 #11 Feb 24 2017 08:54:21
%S A211703 1,3,5,8,9,12,13,16,18,20,21,25,26,28,30,33,34,37,38,41,43,45,46,50,
%T A211703 51,53,55,58,59,62,63,66,68,70,71,75,76,78,80,83,84,87,88,91,93,95,96,
%U A211703 100,101,103,105,108,109,112,113,116,118,120,121,125,126,128
%N A211703 a(n) = n + [n/2] + [n/3] + [n/4], where [] = floor.
%C A211703 See A211701 for a discussion and guide to related sequences.
%H A211703 <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (0, 0, 1, 1, 0, 0, -1).
%F A211703 a(n) = a(n-3) + a(n-4) - a(n-7) for n>=8.
%F A211703 G.f.: x*(1 + 3*x + 5*x^2 + 7*x^3 + 5*x^4 + 4*x^5)/((1 - x)^2*(1 + 2*x + 3*x^2 + 3*x^3 + 2*x^4 + x^5)). - _Ilya Gutkovskiy_, Feb 24 2017
%t A211703 f[n_, m_] := Sum[Floor[n/k], {k, 1, m}]
%t A211703 t = Table[f[n, 4], {n, 1, 90}] (* A211703 *)
%t A211703 FindLinearRecurrence[t]
%t A211703 LinearRecurrence[{0, 0, 1, 1, 0, 0, -1},{1, 3, 5, 8, 9, 12, 13},62] (* _Ray Chandler_, Aug 02 2015 *)
%Y A211703 Cf. A211701.
%K A211703 nonn
%O A211703 1,2
%A A211703 _Clark Kimberling_, Apr 19 2012