# Prove there are infinitely many daffodil numbers

• Jun 16th 2011, 05:36 AM
godelproof
Prove there are infinitely many daffodil numbers
I googled it and found none... can somebody give a proof that there are infinite many of them? thanks(Nod)

BTW, a daffodil number is an n-digit number whose value is equal to the sum of n-th power of each digit, like
• Jun 16th 2011, 06:13 AM
Sudharaka
Re: Prove there are infinitely many daffodil numbers
Quote:

Originally Posted by godelproof
I googled it and found none... can somebody give a proof that there are infinite many of them? thanks(Nod)

BTW, a daffodil number is a n-digit number whose value is equal to the sum of n-th power of each digit, like

Dear godelproof,

It was proved that there are only 88 daffodil numbers (commonly known Narcissistic Numbers) which are in base 10. Please refer, Narcissistic Number -- from Wolfram MathWorld.
• Jun 16th 2011, 06:19 AM
godelproof
Re: Prove there are infinitely many daffodil numbers
Quote:

Originally Posted by Sudharaka
Dear godelproof,

It was proved that there are only 88 daffodil numbers (commonly known Narcissistic Numbers) which are in base 10. Please refer, Narcissistic Number -- from Wolfram MathWorld.

Wow, 88 is a lovely number(Smirk)... I'd thought there were infinitely many of them! thank you~!
• Jun 16th 2011, 06:37 AM
godelproof
Re: Prove there are infinitely many daffodil numbers
Quote:

Originally Posted by Sudharaka
Dear godelproof,

It was proved that there are only 88 daffodil numbers (commonly known Narcissistic Numbers) which are in base 10. Please refer, Narcissistic Number -- from Wolfram MathWorld.

Well... the proof is almost trivial though(Worried)

so let's relax the problem a little... (Wink)
Define a rose number to be an n-digit number whose value is equal to the sum of m-th power of each digit~ like this one given below

And i can think again ...(Cool)
• Jun 16th 2011, 07:25 AM
Sudharaka
Re: Prove there are infinitely many daffodil numbers
Dear godelproof,

Quote:

Wow, 88 is a lovely number... I'd thought there were infinitely many of them! thank you~!
You are welcome.

Quote:

Well... the proof is almost trivial though

so let's relax the problem a little...
Define a rose number to be an n-digit number whose value is equal to the sum of m-th power of each digit~ like this one given below

And i can think again ...
These are called "Perfect digital invariants". It is still not known whether Perfect digital invariants are finite or infinite for a given base. Please refer Narcissistic number - Wikipedia, the free encyclopedia
• Jun 16th 2011, 08:06 AM
godelproof
Re: Prove there are infinitely many daffodil numbers
Quote:

Originally Posted by Sudharaka
It is still not known whether Perfect digital invariants are finite or infinite for a given base. Please refer Narcissistic number - Wikipedia, the free encyclopedia

Thank you! You are being so helpful!
But there doesn't seem to be any articles about PDI in wiki! I can only find some theorems here Digital Invariants: Observations & Theorems
" It is still not known whether Perfect digital invariants are finite or infinite for a given base" where does this conclusion come from?
• Jun 16th 2011, 05:13 PM
Sudharaka
Re: Prove there are infinitely many daffodil numbers
Quote:

Originally Posted by godelproof
Thank you! You are being so helpful!
But there doesn't seem to be any articles about PDI in wiki! I can only find some theorems here Digital Invariants: Observations & Theorems
" It is still not known whether Perfect digital invariants are finite or infinite for a given base" where does this conclusion come from?

It is stated in the Wikipedia link with a citation. Read, Finite or Infinite?
• Jun 16th 2011, 06:08 PM
godelproof
Re: Prove there are infinitely many daffodil numbers
Quote:

Originally Posted by Sudharaka
It is stated in the Wikipedia link with a citation. Read, Finite or Infinite?

Interesting... They can prove that there are infinitely many bases in which there are infinitely many PDIs, but they can NOT prove there whether there are infinitely many PDI in the 10-base case. Hmmm... seems so classic hard number theorical problem: the devil hides in specifics (Cool)