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 A070291 #16 Oct 07 2023 05:06:17
%S A070291 10,5,30,10,2,15,70,20,90,1,110,30,130,35,6,40,170,45,190,2,210,55,
%T A070291 230,60,10,65,270,70,290,3,310,80,330,85,14,90,370,95,390,4,410,105,
%U A070291 430,110,18,115,470,120,490,5,510,130,530,135,22,140,570,145,590,6
%N A070291 a(n) = lcm(10,n)/gcd(10,n).
%H A070291 <a href="/index/Rec#order_20">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,0,0,0,0,0,0,2,0,0,0,0,0,0,0,0,0,-1)
%F A070291 a(n) = A109051(n) / A109013(n). - _R. J. Mathar_, Feb 12 2019
%F A070291 a(n) = 2*a(n-10) - a(n-20). - _R. J. Mathar_, Feb 12 2019
%F A070291 Sum_{k=1..n} a(k) ~ (101/40)*n^2. - _Amiram Eldar_, Oct 07 2023
%t A070291 Table[LCM[10,n]/GCD[10,n],{n,80}] (* _Harvey P. Dale_, Nov 01 2013 *)
%Y A070291 Cf. A070290, A070292, A070293, A109013, A109051.
%K A070291 easy,nonn
%O A070291 1,1
%A A070291 _Amarnath Murthy_, May 10 2002