OFFSET
1,1
LINKS
MATHEMATICA
t = Table[0, {10000}]; k = 1; While[k < 3000000000, a = PowerMod[21, k, k]; If[a < 10001 && t[[a]] == 0, t[[a]] = k]; k++ ]; t (* Robert G. Wilson v, Jun 25 2009 *)
lk[n_]:=Module[{k=1}, While[PowerMod[21, k, k]!=n, k++]; k]; Array[lk, 60] (* The program takes a long time to run *) (* Harvey P. Dale, Oct 22 2016 *)
CROSSREFS
KEYWORD
hard,nonn
AUTHOR
Alexander Adamchuk, Feb 27 2007
EXTENSIONS
a(16) - a(51) from Robert G. Wilson v, Jun 25 2009
STATUS
approved