[seqfan] Ersae a comma to produce a prime

Eric Angelini Eric.Angelini at kntv.be
Mon Apr 8 19:33:09 CEST 2013


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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