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A066995 Numbers k such that sigma(k) divides k*phi(k). 1
1, 6, 15, 28, 84, 95, 140, 182, 190, 248, 270, 287, 308, 357, 420, 455, 477, 496, 570, 672, 744, 819, 840, 910, 1199, 1428, 1488, 1547, 1638, 1722, 1848, 1892, 2295, 2398, 2480, 2660, 2730, 3339, 3417, 3472, 3515, 3596, 3640, 3720, 3780, 3956, 4064, 4095 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
MATHEMATICA
Select[Range[4500], Divisible[# EulerPhi[#], DivisorSigma[1, #]]&] (* Harvey P. Dale, Mar 19 2011 *)
PROG
(PARI) { n=0; for (m=1, 10^10, if ((m*eulerphi(m)) % sigma(m) == 0 , write("b066995.txt", n++, " ", m); if (n==1000, return)) ) } \\ Harry J. Smith, Apr 24 2010
(PARI) isok(n) = frac(n*eulerphi(n)/sigma(n)) == 0; \\ Michel Marcus, Jan 31 2018
(GAP) Filtered([1..10^5], n -> n*Phi(n) mod Sigma(n) = 0); # Muniru A Asiru, Jan 31 2018
CROSSREFS
Sequence in context: A026102 A338024 A144519 * A263896 A295979 A338488
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Jan 27 2002
STATUS
approved

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Last modified April 20 17:12 EDT 2024. Contains 371845 sequences. (Running on oeis4.)