OFFSET
1,1
COMMENTS
A(k) is A258367(k). I believe this was initially defined in Crandall et al. (1997) (in particular pp. 436-437) and it is now common practice for Wieferich searches to report primes with |A| below some predefined limit (for example, the ongoing search at PrimeGrid uses |A| <= 1000).
LINKS
Richard Crandall, Karl Dilcher and Carl Pomerance, A search for Wieferich and Wilson primes, Mathematics of Computation, Vol. 66, No. 217 (1997), pp. 433-449; alternative link.
PrimeGrid, WW Statistics
EXAMPLE
--------------------------------------------
1 | 3 | 4 | 75.000000
2 | 15 | 25 | 60.000000
3 | 21 | 168 | 12.500000
4 | 29 | 1229 | 2.359642
5 | 34 | 9592 | 0.354462
6 | 35 | 78498 | 0.044587
7 | 36 | 664579 | 0.005417
8 | 36 | 5761455 | 0.000625
9 | 41 | 50847534 | 0.000081
PROG
(PARI) a258367(n) = abs(centerlift(Mod(2, n^2)^((n-1)/2))\/n) \\ after Charles R Greathouse IV in A258367
my(i=0, x=10); forprime(p=3, , if(p > x, print1(i, ", "); x=10*x); if(a258367(p) <= 10, i++))
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Felix Fröhlich, Jun 02 2022
STATUS
approved