A339653 - OEIS

A339653

a(n) is 0 if the smallest base-n Wieferich prime is < n, 1 if it is > n and 2 if no base-n Wieferich prime exists.

1, 1, 1, 0, 1, 0, 0, 0, 0, 1, 1, 0, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

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OFFSET

COMMENTS

The value of a(47) is unknown since no base-47 Wieferich prime is known (cf. Fischer).

LINKS

EXAMPLE

For n = 5: The smallest base-5 Wieferich prime is 2 and 2 < 5 so a(5) = 0.

PROG

(PARI) a(n, bound) = forprime(p=1, bound, if(Mod(n, p^2)^(p-1)==1, if(p < n, return(0), return(1)))); ("bound reached")

for(n=2, 50, print1(a(n, 1e8), ", ")) \\ Execute the function like this to search the bases to 10^8

CROSSREFS

KEYWORD

nonn,hard,more

AUTHOR

STATUS

approved