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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A082681 Denominator of sum_{i=n(n-1)/2+1..n(n+1)/2} 1/i. 1
1, 6, 60, 2520, 20020, 1627920, 124324200, 1694579040, 446626220040, 73706596563600, 35444732266944, 24569517992362200, 3290057629552053360, 551042196782556679200, 71028805196838414285360 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..15.

PROG

(PARI) a(n) = denominator(sum(i = n*(n-1)/2+1, n*(n+1)/2, 1/i)); \\ Michel Marcus, Aug 29 2013

CROSSREFS

Numerator is in A081971. a(n) is a divisor of A061431(n).

Sequence in context: A271681 A010574 A271682 * A061431 A261523 A318131

Adjacent sequences:  A082678 A082679 A082680 * A082682 A082683 A082684

KEYWORD

nonn,frac

AUTHOR

Dean Hickerson, Apr 10 2003

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 April 23 08:47 EDT 2019. Contains 322381 sequences. (Running on oeis4.)