Problems & Puzzles: Puzzles

 

 

Problems & Puzzles: Puzzles

Puzzle 1274 A modified Buss's Conjecture

On June 25, 2026, Davide Rotondo sent a new Conjecture & Puzzle:


This is my last conjecture regarding Buss. References, 1 & 2

Construct the following Table according to the following algorithm:

Start with f(1)=1.
Calculate the smallest prime number obtained by concatenating the smallest number (other than 1) to f(n).
 Calculate R(n) based on the value used in the concatenation to obtain that prime number.
 Calculate f(n+1) = f(n)R(n).


Here are the first ten rows:

f(n) Smallest prime number obtained  by concatenating the smallest number  (other than 1) to f(n) R(n)
1 1(3) 3
3 3(7) 7
21 21(11) 11
231 231(17) 17
3927 3927(23) 23
90321 90321(19) 19
1716099 1716099(13) 13
22309287 22309287(29) 29
646969323 646969323(37) 37
2.3938E+10 23937864951(41) 41


Davide Rotondo conjectures that the third column will display all and only odd prime integers (except 5) withou any repetition.

He has calulated the following values for the third column, R(n):
[3, 7, 11, 17, 23, 19, 13, 29, 37, 41, 67, 53, 71, 47, 97, 109, 113, 107, 31, 151, 59, 73, 127, 43, 131, 101, 137, 157, 103, 227, 149, 181, 223, 193, 211, 241, 167, 251, 79, 83, 163, 347, 197, 173, 293, 263, 367, 307, 257, 463, 383, 239, 179, 419, 571, 577, 283, 89, 373, 823, 379, 233, 541, 929, 617, 619, 631, 709, 673, 1231, 547, 199, 947, 1171, 449, 397, 311, 953, 349, 191, 409, 139, 317, 601, 431, 271, 457, 613, 509, 719, 811, 647, 659, 967]
 
Q1. Can you verify at least the Rotondo's list up to 967

Q2. Can you extend your list and after the end of your list name the smallest prime absent

Q3. Can you prove the Rotondo's conjecture
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