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A066463 Numbers n such that EulerPhi(sigma(EulerPhi(n))) = EulerPhi(n). 1
1, 2, 3, 4, 6, 13, 15, 16, 20, 21, 24, 26, 28, 30, 36, 42, 241, 255, 256, 272, 287, 305, 320, 325, 340, 369, 384, 385, 408, 429, 465, 480, 482, 488, 495, 496, 510, 525, 572, 574, 610, 616, 620, 650, 700, 732, 738, 744, 770, 779, 792, 793, 803, 858, 900, 905 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Harry J. Smith, Table of n, a(n) for n=1,...,1000

MATHEMATICA

Select[Range[1, 10^3], EulerPhi[DivisorSigma[1, EulerPhi[ # ]]] == EulerPhi[ # ] &]

PROG

(PARI) { n=0; for (m=1, 10^10, if (eulerphi(sigma(eulerphi(m))) == eulerphi(m), write("b066463.txt", n++, " ", m); if (n==1000, return)) ) } [From Harry J. Smith, Feb 16 2010]

CROSSREFS

Sequence in context: A018738 A018765 A096988 * A073146 A038767 A188715

Adjacent sequences:  A066460 A066461 A066462 * A066464 A066465 A066466

KEYWORD

nonn

AUTHOR

Joseph L. Pe, Jan 02 2002

STATUS

approved

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Last modified April 25 00:33 EDT 2014. Contains 240990 sequences.