OFFSET
1,2
COMMENTS
All powers of two are present.
MATHEMATICA
fQ[n_] := !PrimeQ@ n && PowerMod[2, n - 1, n] == PowerMod[4, n - 1, n]; Select[ Range@ 10000, fQ]
CROSSREFS
KEYWORD
nonn
AUTHOR
Juri-Stepan Gerasimov, Dec 07 2010
STATUS
approved