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 A227109 #14 Sep 08 2022 08:46:05
%S A227109 0,5,20,15,40,5,60,35,80,45,20,55,120,65,140,15,160,85,180,95,8,105,
%T A227109 220,115,240,25,260,135,280,145,60,155,320,165,340,35,360,185,380,195,
%U A227109 80,205,420,215,440,9,460,235,480,245,100,255,520,265,540,55,560
%N A227109 Numerators of harmonic mean H(n, 5), n >= 0.
%C A227109 a(n) = numerator(H(n, 5)) = numerator(10*n/(n+5)), n>=0, with H(n, 5) the harmonic mean of n and 5.
%C A227109 The corresponding denominator is given in A227108(n), n>= 0.
%C A227109 a(n+5), n>=0, is the fifth column (m=5) of the triangle A227041.
%F A227109 a(n) = numerator(10*n/(n+5)), n >= 0.
%F A227109 a(n) = 10*n/gcd(n+5,10*n) = 10*n/gcd(n+5,50), n >= 0.
%e A227109 The rationals H(n,5) begin: 0, 5/3, 20/7, 15/4, 40/9, 5, 60/11, 35/6, 80/13, 45/7, 20/3, 55/8, 120/17, 65/9, ...
%t A227109 Table[Numerator[(10 n / (n + 5))], {n, 0, 60}] (* _Vincenzo Librandi_, Nov 06 2016 *)
%o A227109 (PARI) a(n) = numerator(10*n/(n+5)); \\ _Michel Marcus_, Nov 06 2016
%o A227109 (Magma) [Numerator(10*n/(n+5)): n in [0..60]]; // _Vincenzo Librandi_, Nov 06 2016
%Y A227109 Cf. A227041(n+5,5), A227108 (denominator).
%K A227109 nonn,frac,easy
%O A227109 0,2
%A A227109 _Wolfdieter Lang_, Jul 01 2013