All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars    
perplexus dot info

Home > Just Math
Nice sum (Posted on 2004-08-24) Difficulty: 3 of 5
Give a closed expression for the infinite sum:

1/1 + 2/(2+3) + 3/(4+5+6) + 4/(7+8+9+10) + ...

See The Solution Submitted by Federico Kereki    
Rating: 2.7500 (4 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Some Thoughts starting observation | Comment 1 of 13
Successive differences on the denominators shows them to follow a third degree polynomial.  That turns out to be (i^3+i)/2.  The terms are thus 2i/(i^3+i), which reduces to 2/(i^2+1).
  Posted by Charlie on 2004-08-24 12:54:58
Please log in:
Remember me:
Sign up! | Forgot password

Search body:
Forums (0)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (0)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Copyright © 2002 - 2018 by Animus Pactum Consulting. All rights reserved. Privacy Information