A sequence of natural numbers is determined by the following formula, A[n+1] = a[n] + f(n) Where f(n) is the product of digits in a[n]. Is there an a[1] such that the above sequence is unbounded?

## Welcome to BrainDen.com - Brain Teasers Forum

Welcome to BrainDen.com - Brain Teasers Forum. Like most online communities you must register to post in our community, but don't worry this is a simple free process. To be a part of BrainDen Forums you may create a new account or sign in if you already have an account. As a member you could start new topics, reply to others, subscribe to topics/forums to get automatic updates, get your own profile and make new friends. Of course, you can also enjoy our collection of amazing optical illusions and cool math games. If you like our site, you may support us by simply clicking Google "+1" or Facebook "Like" buttons at the top. If you have a website, we would appreciate a little link to BrainDen. Thanks and enjoy the Den :-) |

Guest Message by DevFuse

# An unbounded sequence?

Started by BMAD, Jan 28 2014 10:15 PM

2 replies to this topic

### #1

Posted 28 January 2014 - 10:15 PM

### #2

Posted 02 February 2014 - 02:41 PM

Spoiler for looks like

*The greatest challenge to any thinker is stating the problem in a way that will allow a solution.*

- Bertrand Russell

### #3

Posted 02 February 2014 - 02:46 PM

your logic is sound and the last of your explanation is on the correct track

#### 0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users