[seqfan] Re: Ersae a comma to produce a prime

DAN_CYN_J dan_cyn_j at comcast.net
Mon Apr 8 21:40:22 CEST 2013



Hi Eric, 

  

Does your sequence fail @ the 14th term which is 23? 
Unless I am counting wrong, it removes the comma between [61,34]  

Not a prime. 

  

Dan 


----- Original Message -----




From: "Eric Angelini" <Eric.Angelini at kntv.be> 
To: "Sequence Fanatics Discussion list" <seqfan at list.seqfan.eu> 
Sent: Monday, April 8, 2013 1:33:09 PM 
Subject: [seqfan] Ersae a comma to produce a prime 


Hello Seqfans, 

If you concatenate the terms separated by the T-th comma in S, 
you'll read a prime number. 

T is any term of S and S doesn't show twice the same integer. 
Hopefully S is also the lexicographically first such sequence: 

S = 1,3,4,7,9,6,13,19,10,21,11,17,14,23,33,16,27,29,20,39,31,37,61,24,41,53,26,47,51,30,... 

Example : 

-- the first term is 1 ; so, if you erase the 1st comma in S 
   you'll read 13 -- which is a prime; 
-- the second term is 3 ; so, if you erase the 3rd comma in S 
   you'll read 47 -- which is a prime; 
-- the third term is 4 ; so, if you erase the 4th comma in S 
   you'll read 79 -- which is a prime; 
-- the fourth term is 7 ; so, if you erase the 7th comma in S 
   you'll read 1319 -- which is a prime; 
-- the fifth term is 9 ; so, if you erase the 9th comma in S 
   you'll read 1021 -- which is a prime; 
... 

Best, 
É. 




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