login
A078557
Squarefree balanced numbers (i.e., squarefree members of A020492).
4
1, 2, 3, 6, 14, 15, 30, 35, 42, 70, 78, 105, 190, 210, 357, 418, 570, 714, 910, 1045, 1254, 2090, 2730, 3135, 4522, 4674, 5278, 6270, 10659, 12441, 13566, 14630, 15834, 16770, 20026, 21318, 23374, 24871, 24882, 24969, 25070, 25714, 27170, 29029
OFFSET
1,2
LINKS
EXAMPLE
210 = 2*3*5*7, sigma(210) = 576, phi(210) = 48, 576/48 = 12.
MATHEMATICA
Do[s=DivisorSigma[1, n]/EulerPhi[n]; If[IntegerQ[s]&&!Equal[MoebiusMu[n], 0], k=k+1; Print[n]], {n, 1, 2100000}]
CROSSREFS
Cf. A020492.
Sequence in context: A258077 A121556 A123041 * A005537 A306600 A282351
KEYWORD
nonn
AUTHOR
Labos Elemer, Dec 06 2002
STATUS
approved