Problems & Puzzles:
Puzzle 126. Some conspicuous probable primes
1.- Find the first probable prime in the
1.a) 1, 122, 122333, 1223334444,
1.b) 1, 221, 333221, 4444333221, etc.
2.- Find the fourth probable prime in the
following generalized palindromic (**) sequence:
(primes, as always, are in blue)
(*) I'm posting this 3 questions with the hope of producing a probable
prime that may serve to get another record for the Titanix
code. This requires that at least one of the probable primes asked has
less than 4000 digits and more than 3106 digits. Why? The current record
for this powerful tool - Titanix - is the now prime number (348^1223-1)/347,
3106 decimal digits, proved to be prime very recently by Giovanni &
Marco La Barbera. If all of these 3 probable primes are too larger
than 4000 digits, then the task will have to be solved in the near?
future...). If all the asked probable primes are out of the suggested
range maybe you would be so kind to submit another
digital-conspicuous probable prime & candidate to be the record for
the Titanix code, with a quantity of digits in the proper range.
(**) A generalized palindrome sequence is a
concatenation of numbers abc...xyz such that a=z, b=y, c=x, etc. The nut
or center of the number may be empty (for a gp with an even quantity of
concatenated numbers) or an arbitrary number (for a gp with an odd
quantity of concatenated numbers). If and only if every concatenated
number in the gp is palindrome then, gp is also a classical or real
J. K. Andersen wrote:
I tested the 3 sequences with PrimeForm/GW. They grow
so quickly that it
would have required a lot of luck to get a prp in Titanix/Primo record
range. No primes or prp's were found.
1.a) No primes in the first 708 terms. Term 709 has 750090 digits.
1.b) No primes in the first 599 terms. Term 600 has 535905 digits.
2. No primes in term 6 to term 471. Term 472 has 658362 digits.
I think the first term should be 1 and not 11.
Then there are only two small primes: Term 3 and term 5.