Problems & Puzzles: Puzzles

 

 

Problems & Puzzles: Puzzles

Puzzle 1264 A follow up to Puzzle 973

In 2009, J. K. Andersen got the following twin & empirps:

10^499+X+/-1 for X=174295123052

 10^499+174295123052 +1 is prime
10^499+174295123052 -1 is prime
Rev(10^499+174295123052 +1) is prime
Rev(10^499+174295123052 -1) is prime

(The four 500 digits primes verified by CR using ECM)
Perhaps it's time to get something larger than this.
Q.  Find larger examples of these kind





From April 4-11, 2026, contributions came from Simon Cavegn

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Simon wrote:

182348281 * 10^1000 + 775222951
182348281 * 10^1000 + 775222951 + 2
RevDigits(182348281 * 10^1000 + 775222951, 10)
RevDigits(182348281 * 10^1000 + 775222951 + 2, 10)


1009 digits primes.

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 On May 20, 2026, Simon wrote again:

 398671151113 * 10^1607 + 900188848051
398671151113 * 10^1607 + 900188848053
150848881009 * 10^1607 + 311151176893
350848881009 * 10^1607 + 311151176893

1619 digit primes


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