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A066930
Numbers n such that phi(sigma(n)) divides sigma(phi(n)).
4
1, 7, 9, 29, 71, 97, 109, 121, 139, 142, 175, 183, 194, 215, 225, 242, 244, 261, 278, 311, 344, 349, 355, 430, 497, 509, 516, 533, 556, 571, 605, 622, 631, 647, 673, 709, 729, 791, 817, 859, 911, 923, 1021, 1066, 1112, 1119, 1142, 1207, 1243, 1262, 1277
OFFSET
1,2
LINKS
MATHEMATICA
Select[Range[1300], Divisible[DivisorSigma[1, EulerPhi[#]], EulerPhi[ DivisorSigma[ 1, #]]]&] (* Harvey P. Dale, Dec 15 2021 *)
PROG
(PARI) { n=0; for (m=1, 10^10, if (sigma(eulerphi(m)) % eulerphi(sigma(m)) == 0, write("b066930.txt", n++, " ", m); if (n==1000, return)) ) } \\ Harry J. Smith, Apr 08 2010
CROSSREFS
Cf. A033632.
Sequence in context: A030404 A242505 A263826 * A247192 A154260 A309199
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Jan 26 2002
STATUS
approved