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A226385 Numbers n such that rad(phi(n)) > phi(rad(n)), where rad(n) is the squarefree kernel of n, and phi is Euler's totient function. 1
4, 8, 9, 16, 18, 25, 27, 32, 36, 49, 50, 54, 64, 72, 75, 81, 98, 99, 100, 108, 121, 125, 128, 144, 147, 150, 162, 169, 175, 196, 198, 200, 207, 216, 225, 242, 243, 245, 250, 256, 288, 289, 294, 297, 300, 324, 338, 343, 350, 361, 363, 375, 392, 396, 400, 414 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

MATHEMATICA

rad[n_] := Product[fa[n][[i, 1]], {i, Length[fa[n]]}]; fa = FactorInteger; Select[Range[500], rad[EulerPhi[#]] > EulerPhi[rad[#]] &]

PROG

(PARI) rad(n)=my(f=factor(n)[, 1]); prod(i=1, #f, f[i])

is(n)=rad(eulerphi(n))>eulerphi(rad(n)) \\ Charles R Greathouse IV, Dec 27 2013

CROSSREFS

Cf. A007947, A000010, A226384, A226386.

Sequence in context: A034024 A299117 A140269 * A070003 A325661 A073539

Adjacent sequences:  A226382 A226383 A226384 * A226386 A226387 A226388

KEYWORD

nonn

AUTHOR

José María Grau Ribas, Jun 05 2013

STATUS

approved

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Last modified August 5 21:18 EDT 2020. Contains 336213 sequences. (Running on oeis4.)