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 A211704 #16 Sep 08 2022 08:46:02
%S A211704 1,3,5,8,10,13,14,17,19,22,23,27,28,30,33,36,37,40,41,45,47,49,50,54,
%T A211704 56,58,60,63,64,68,69,72,74,76,78,82,83,85,87,91,92,95,96,99,102,104,
%U A211704 105,109,110,113,115,118,119,122,124,127,129,131,132,137,138
%N A211704 a(n) = n + [n/2] + [n/3] + [n/4] + [n/5], where []=floor.
%C A211704 See A211701 for a discussion and guide to related sequences.
%H A211704 <a href="/index/Rec#order_11">Index entries for linear recurrences with constant coefficients</a>, signature (-1,-1,0,1,2,2,1,0,-1,-1,-1).
%F A211704 a(n) = -a(n-1)-a(n-2)+a(n-4)+2*a(n-5)+2*a(n-6)+a(n-7)-a(n-9)-a(n-10)-a(n-11) for n>=12.
%t A211704 f[n_, m_] := Sum[Floor[n/k], {k, 1, m}]
%t A211704 t = Table[f[n, 5], {n, 1, 90}] (* A211704 *)
%t A211704 FindLinearRecurrence[t]
%t A211704 Table[Total[Table[Floor[n/i],{i,5}]],{n,70}] (* or *) LinearRecurrence[ {-1,-1,0,1,2,2,1,0,-1,-1,-1},{1,3,5,8,10,13,14,17,19,22,23},70] (* _Harvey P. Dale_, Jan 19 2015 *)
%o A211704 (Magma) [n+Floor(n/2)+Floor(n/3)+Floor(n/4)+Floor(n/5): n in [1..70]]; // _Vincenzo Librandi_, Jun 23 2015
%Y A211704 Cf. A211701.
%K A211704 nonn,easy
%O A211704 1,2
%A A211704 _Clark Kimberling_, Apr 19 2012