OFFSET
1,1
COMMENTS
The sequence is complete (cf. Michon).
Are these primes necessarily prime factors of A007663(i)/p when p = prime(i) is a Wieferich prime (A001220)?
Note the following curious observation: 3 * 7 * 79 * 2731 * 8191 * 121369 * 22366891 = 100743818301219097892181. That number is a repdigit in bases 4 and 64 and undulating in bases 2, 8, 128, 2048 and 8192. Compare that to observations from John Blythe Dobson (cf. Dobson).
LINKS
J. B. Dobson, A note on the two known Wieferich primes
Gerard P. Michon, Wieferich Primes 1093 and 3511
PROG
(PARI) fq(n) = (2^(n-1)-1)/n
my(x=fq(1093)/1093, y=fq(3511)/3511); forprime(p=1, , if(Mod(x, p)==0 && Mod(y, p)==0, print1(p, ", ")))
CROSSREFS
KEYWORD
nonn,fini,full
AUTHOR
Felix Fröhlich, Apr 28 2021
STATUS
approved