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%I #8 Jul 03 2013 12:02:23
%S 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 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 28,57,29,59,6,61,31,63,32,13,33,67,34,69,7,71,36,73,37,3,38,77
%N Denominators of harmonic mean H(n,5), n >= 0.
%C 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 The corresponding numerators are given in A227109(n), n >= 0.
%C a(n+5), n>=0, is the fifth column (m=5) of the triangle A227042.
%F a(n) = denominator(10*n/(n+5)), n >= 0.
%F a(n) = (n+m)/gcd(n+5, 10*n) = (n+5)/gcd(n+5, 50), n >= 0.
%e 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 Cf. A227042(n+5,5), A227109 (numerators).
%K nonn,frac,easy
%O 0,2
%A _Wolfdieter Lang_, Jul 01 2013
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