OFFSET
1,1
COMMENTS
MATHEMATICA
Do[f=Mod[Sum[Sum[PowerMod[Prime[i], j, n], {i, 1, n-1}], {j, 1, n-1}], n]; If[f==0&&!PrimeQ[n], Print[n]], {n, 2, 512}]
CROSSREFS
KEYWORD
hard,more,nonn
AUTHOR
Alexander Adamchuk, Oct 13 2006, Oct 15 2006, Oct 22 2006
EXTENSIONS
More terms from Max Alekseyev, Sep 13 2009
STATUS
approved