A068919 Squarefree orders of non-Abelian groups.

6, 10, 14, 21, 22, 26, 30, 34, 38, 39, 42, 46, 55, 57, 58, 62, 66, 70, 74, 78, 82, 86, 93, 94, 102, 105, 106, 110, 111, 114, 118, 122, 129, 130, 134, 138, 142, 146, 154, 155, 158, 165, 166, 170, 174, 178, 182, 183, 186, 190, 194, 195, 201, 202, 203, 205, 206

Offset

1,1

Comments

This set is the difference A005117 \ A003277, that is, the squarefree numbers that are not cyclic (A003277). - Jeppe Stig Nielsen, Sep 25 2017

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Mathematica

Complement[Select[Range[206], SquareFreeQ[#] &],
Select[Range[206], FiniteGroupCount[#] == 1 &]] (* Geoffrey Critzer, Nov 28 2015 *)

Prog

(Haskell)
a068919 n = a068919_list !! (n-1)
a068919_list = filter ((== 1) . a008966) a056868_list
-- Reinhard Zumkeller, Jun 28 2013
(PARI) is(n)=issquarefree(n)&&gcd(n, eulerphi(n))!=1 \\ Jeppe Stig Nielsen, Sep 25 2017

Crossrefs

Intersection of A060652 and A005117.

Cf. A064899.

Also intersection of A056868 and A005117. - Reinhard Zumkeller, Jun 28 2013

Cf. A008966.

Sequence in context: A315222 A315223 A239699 * A060650 A350586 A068198

Adjacent sequences: A068916 A068917 A068918 * A068920 A068921 A068922

Keyword

nonn

Author

Sharon Sela (sharonsela(AT)hotmail.com), Mar 29 2002

Status

approved