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A069087 Numbers n such that (1/n)*sum(k=1,n,core(k))>phi(n) where core(n)=A007913(n) is the squarefree part of n: the smallest number such that n*a(n) is a square and phi(n)=A000010(n) is the Euler totient function. 2
2, 6, 12, 18, 24, 30, 36, 42, 48, 60, 66, 72, 78, 84, 90, 96, 102, 114, 120, 126, 132, 138, 144, 150, 156, 168, 174, 180, 186, 198, 204, 210, 222, 228, 234, 240, 246, 252, 258, 264, 270, 276, 282, 294, 300, 306, 312, 318, 330, 336, 342, 348, 360, 372, 378, 390 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Equivalently, n such that A069891(n) > n*phi(n).

The listed terms are all even, but there are some odd terms, including n = 111546435 = 3*5*7*11*13*17*19*23, for which A069891(n)=4093453424286382 and n*phi(n) = 4070927302041600.

LINKS

Table of n, a(n) for n=1..56.

PROG

(PARI) is(n)=sum(k=1, n, core(k)) > n*eulerphi(n) \\ Charles R Greathouse IV, Feb 21 2013

CROSSREFS

Sequence in context: A066080 A319270 A071707 * A304450 A085345 A265843

Adjacent sequences:  A069084 A069085 A069086 * A069088 A069089 A069090

KEYWORD

nonn

AUTHOR

Benoit Cloitre, Apr 05 2002

EXTENSIONS

Edited by Dean Hickerson, Apr 09 2002

STATUS

approved

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Last modified March 26 18:36 EDT 2019. Contains 321511 sequences. (Running on oeis4.)