       RE: Prime Puzzle with Mathematica

• To: mathgroup at smc.vnet.net
• Subject: [mg92732] RE: [mg92680] Prime Puzzle with Mathematica
• From: "Tony Harker" <a.harker at ucl.ac.uk>
• Date: Sat, 11 Oct 2008 06:47:36 -0400 (EDT)
• References: <200810100835.EAA07106@smc.vnet.net>

```]-> -----Original Message-----
]-> From: amzoti [mailto:amzoti at gmail.com]
]-> Sent: 10 October 2008 09:35
]-> To: mathgroup at smc.vnet.net
]-> Subject: [mg92680] Prime Puzzle with Mathematica
]->
]-> Hi All,
]->
]-> trying to find an efficient way to this in Mathematica.
]->
]-> I found the answer - but it was a manual list manipulation
]-> - and it was ugly!
]->
]-> Any suggestions?
]->
]-> 3 Nice Primes:
]->
]-> Find three 2-digit prime numbers such that:
]->
]->     * The average of any two of the three is a prime number, and
]->     * The average of all three is also a prime number
]->
]-> Thanks!
]->
]-> ~A
]->
]->

Here's a brute force method:

Select[Union[Map[Sort, Flatten[Outer[List, #, #, #], 2]]] &[
Select[Range[10, 99], PrimeQ]], (Length[Union[#]] == 3) &&
PrimeQ[(#[] + #[])/2] && PrimeQ[(#[] + #[])/2] &&
PrimeQ[(#[] + #[])/2] &&
PrimeQ[(#[] + #[] + #[])/3] &]

Tony

```

• Prev by Date: Re: Prime Puzzle with Mathematica [CORRECTION]
• Next by Date: Re: Mathematica vs Latex
• Previous by thread: RE: Prime Puzzle with Mathematica
• Next by thread: Re: Prime Puzzle with Mathematica