A153514 Terms of A122780 which are not Carmichael numbers A002997.

1, 6, 66, 91, 121, 286, 671, 703, 726, 949, 1541, 1891, 2665, 2701, 3281, 3367, 3751, 4961, 5551, 7107, 7381, 8205, 8401, 8646, 11011, 12403, 14383, 15203, 15457, 16471, 16531, 18721, 19345, 23521, 24046, 24661, 24727, 28009, 29161, 30857, 31621

Offset: 1

Author

Artur Jasinski, Dec 28 2008

Keywords

• nonn

Comments

For the intersection of this sequence and A153508, see A153513.

Links

• Robert Israel, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A002997, A122780, A153508, A153513.

Programs

Maple

filter:= proc(n) local p;
  if isprime(n) or (3 &^n - 3 mod n <> 0) then return false fi;
  if n::even then return true fi;
  if not numtheory:-issqrfree(n) then return true fi;
  for p in numtheory:-factorset(n) do
    if n-1 mod (p-1) <> 0 then return true fi
  od;
false
end proc:
filter(1):= true:
select(filter, [$1..10^5]); # Robert Israel, Jan 29 2017

Mathematica

okQ[n_] := !PrimeQ[n] && PowerMod[3, n, n] == Mod[3, n] && Mod[n, CarmichaelLambda[n]] != 1;
Select[Range[10^5], okQ] (* Jean-François Alcover, Mar 27 2019 *)