OFFSET
1,1
COMMENTS
Sequence is fairly regular; 437 numbers below 1000 have 4 square roots of 2 mod k; 4796 below 10^4; 47276 below 10^5; and 452172 below 10^6.
EXAMPLE
2 has square roots 11, 45, 74, 108 mod 119; e.g., 11^2 == 2 (mod 119).
MATHEMATICA
Select[Range[3000], Length@PowerModList[2, 1/2, #] == 4 &]
CROSSREFS
KEYWORD
nonn
AUTHOR
Dale Taylor, May 17 2016
STATUS
approved