A091454 -id:A091454 - cp's OEIS frontend

A066765 Numbers k such that phi(k) < k/5.

30030, 39270, 43890, 46410, 51870, 53130, 60060, 78540, 87780, 90090, 92820, 103740, 106260, 117810, 120120, 131670, 139230, 150150, 155610, 157080, 159390, 175560, 180180, 185640, 196350, 207480, 210210, 212520, 219450, 232050, 235620

Offset: 1

Jason Earls, Jan 17 2002

Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1000 from Harry J. Smith)

Cf. A000010 (phi), A091454.

Select[Range[250000], EulerPhi[#] < #/5 &] (* Amiram Eldar, Apr 07 2024 *)

PARI
```
for(n=1,10^8, if(eulerphi(n)
				
```

{ n=0; for (m=1, 10^10, if (eulerphi(m) < m/5, write("b066765.txt", n++, " ", m); if (n==1000, return)) ) } \\ Harry J. Smith, Mar 24 2010

list(lim)=my(v=List()); forfactored(n=30030,lim\1, if(5*eulerphi(n)Charles R Greathouse IV, Jan 16 2025

a(n) ~ kn for some constant k. k seems to be near 6500. - Charles R Greathouse IV, Jan 16 2025

A091455 Integers n such that 3*phi(n) < n that are not multiples of smaller integers with this property.

Original entry on oeis.org

30, 42, 66, 78, 102, 114, 138, 174, 186, 222, 246, 258, 282, 318, 354, 366, 402, 426, 438, 474, 498, 534, 582, 606, 618, 642, 654, 678, 762, 770, 786, 822, 834, 894, 906, 910, 942, 978, 1002, 1038, 1074, 1086, 1146, 1158, 1182, 1190, 1194, 1266, 1330

Offset: 1

Robert G. Wilson v, Jan 10 2004

nonn

Cf. A091454.

a = {}; Do[ ep = EulerPhi[n]; If[ 3ep < n && Union[ Map[ IntegerQ, n/a]] != {False, True}, AppendTo[a, n]; Print[n]], {n, 1, 1361}]

cp's OEIS Frontend

A066765 Numbers k such that phi(k) < k/5.

Views

Author

Keywords

Links

Crossrefs

Programs

Mathematica

PARI

PARI

PARI

Formula

A091455 Integers n such that 3*phi(n) < n that are not multiples of smaller integers with this property.

Views

Author

Keywords

Crossrefs

Programs

Mathematica