login
This site is supported by donations to The OEIS Foundation.

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A227108 Denominators of harmonic mean H(n,5), n >= 0. 2
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 (list; graph; refs; listen; history; text; internal format)
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: A274511 A179706 A231325 * A016619 A066538 A216627

Adjacent sequences:  A227105 A227106 A227107 * A227109 A227110 A227111

KEYWORD

nonn,frac,easy

AUTHOR

Wolfdieter Lang, Jul 01 2013

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 12 15:11 EST 2019. Contains 329960 sequences. (Running on oeis4.)