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

Home > Numbers > Sequences
....and the 100th member is (Posted on 2021-10-04) Difficulty: 2 of 5
The increasing sequence 1, 5, 6, 25, 26, 30, 31, 125, 126, … consists of all positive integers that can be formed by summing up distinct powers of 5 - from 1 to N presented in increasing order.
That is, 1 = 5^0, 5 = 5^1, 6 = 5^0 + 5^1, etc, etc.

What’s the 100th integer in this sequence?

No Solution Yet Submitted by Ady TZIDON    
Rating: 3.3333 (3 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
soln | Comment 1 of 4
we count to 100 in binary (1100100) for the 100th. Each digit is 
0 or 1 times 5^n, where the digits go n=0,1,...

100th is 5^6 + 5^5 + 5^2 = 18775

  Posted by Steven Lord on 2021-10-04 08:50:40
Please log in:
Login:
Password:
Remember me:
Sign up! | Forgot password


Search:
Search body:
Forums (0)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (10)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Chatterbox:
Copyright © 2002 - 2024 by Animus Pactum Consulting. All rights reserved. Privacy Information