A227108 Denominators of harmonic mean H(n,5), n >= 0.

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, 16, 33, 17, 7, 18, 37, 19, 39, 4, 41, 21, 43, 22, 9, 23, 47, 24, 49, 1, 51, 26, 53, 27, 11, 28, 57, 29, 59, 6, 61, 31, 63, 32, 13, 33, 67, 34, 69, 7, 71, 36, 73, 37, 3, 38, 77

Offset

0,2

Comments

a(n) = denominator(H(n,5)) = denominator(10*n/(n+5)), n>=0, with H(n,5) the harmonic mean of n and 5.

The corresponding numerators are given in A227109(n), n >= 0.

a(n+5), n>=0, is the fifth column (m=5) of the triangle A227042.

Links

Table of n, a(n) for n=0..72.

Formula

a(n) = denominator(10*n/(n+5)), n >= 0.

a(n) = (n+m)/gcd(n+5, 10*n) = (n+5)/gcd(n+5, 50), n >= 0.

Example

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, ...

Crossrefs

Cf. A227042(n+5,5), A227109 (numerators).

Sequence in context: A371332 A179706 A231325 * A367712 A016619 A368069

Adjacent sequences: A227105 A227106 A227107 * A227109 A227110 A227111

Keyword

nonn,frac,easy

Author

Wolfdieter Lang, Jul 01 2013

Status

approved