OFFSET
1,11
COMMENTS
According to the conjecture in A242441, a(n) > 0 for all n > 1848.
LINKS
Zhi-Wei Sun, Table of n, a(n) for n = 1..10000
EXAMPLE
a(9) = 1 since 2^2*7 == 1 (mod 9).
MATHEMATICA
r[k_, n_]:=PowerMod[k^2, -1, n]
Do[m=0; Do[If[GCD[k, n]==1&&PrimeQ[r[k, n]], m=m+1], {k, 1, Sqrt[n-1]}]; Print[n, " ", m]; Continue, {n, 1, 80}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Zhi-Wei Sun, May 14 2014
STATUS
approved