A Conjecture on Williams Numbers
In 1977, Williams
asked whether there are any Carmichael numbers n with
an odd number of prime divisors and the
additional property that for each prime p | n,
p + 1
| n + 1.
We [Zhang 2015, §7] tabulated a table of 1029
primes: ( Download the text file of the 1029 primes )
787
907
1087
…
224489273360340970879
4194019937445612397579
4905729483343410746599
and reasonably conjecture that there could be at least 224 ( = 16,777,216) Williams numbers made up from them.
CHALLENGE: I offer a prize of $500 to the first person who communicates to
me a Williams number made up from the 1029
primes.
Claimants must state the prime factorization
of any numbers submitted.
(Let W0 be the smallest Williams number, then for integers N < W0 only one iteration of the OPQBT (see [Zhang
2002])
will decide whether N is prime or not. However, our prize does
not ask you to submit W0
, only one Williams number is enough to win
the prize of
$500. Finding W0 is the next project. )
2020-12-06
2022-1-28