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Guest Message by DevFuse

# An unbounded sequence?

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Posted 28 January 2014 - 10:15 PM

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?

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### #2 bonanova

bonanova

bonanova

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Posted 02 February 2014 - 02:41 PM

Spoiler for looks like

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

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Posted 02 February 2014 - 02:46 PM

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

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