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.

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

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: A339462 A140269 A339744 * A070003 A325661 A073539

Adjacent sequences: A226382 A226383 A226384 * A226386 A226387 A226388

Keyword

nonn

Author

José María Grau Ribas, Jun 05 2013

Status

approved