OFFSET
1,1
COMMENTS
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
MAPLE
filter:= proc(n) local r, a, b;
r:= numtheory:-phi(n);
a:= padic:-ordp(r, 2);
b:= padic:-ordp(r, 3);
if b = 0 then return false fi;
r = 2^a*3^b;
end proc:
select(filter, [seq(i, i=3..1000, 2)]); # Robert Israel, May 11 2020
MATHEMATICA
Do[If[Take[FactorInteger[EulerPhi[2n+1]][[ -1]], 1]=={3}, Print[2n+1]], {n, 1, 10000}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Artur Jasinski, Dec 13 2006
EXTENSIONS
Edited by Don Reble, Apr 24 2007
STATUS
approved