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 A227108 #8 Jul 03 2013 12:02:23 %S A227108 1,3,7,4,9,1,11,6,13,7,3,8,17,9,19,2,21,11,23,12,1,13,27,14,29,3,31, %T A227108 16,33,17,7,18,37,19,39,4,41,21,43,22,9,23,47,24,49,1,51,26,53,27,11, %U A227108 28,57,29,59,6,61,31,63,32,13,33,67,34,69,7,71,36,73,37,3,38,77 %N A227108 Denominators of harmonic mean H(n,5), n >= 0. %C A227108 a(n) = denominator(H(n,5)) = denominator(10*n/(n+5)), n>=0, with H(n,5) the harmonic mean of n and 5. %C A227108 The corresponding numerators are given in A227109(n), n >= 0. %C A227108 a(n+5), n>=0, is the fifth column (m=5) of the triangle A227042. %F A227108 a(n) = denominator(10*n/(n+5)), n >= 0. %F A227108 a(n) = (n+m)/gcd(n+5, 10*n) = (n+5)/gcd(n+5, 50), n >= 0. %e A227108 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, ... %Y A227108 Cf. A227042(n+5,5), A227109 (numerators). %K A227108 nonn,frac,easy %O A227108 0,2 %A A227108 _Wolfdieter Lang_, Jul 01 2013