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A074891
Numbers n such that sigma(n) = phi(3n).
4
15, 35, 357, 1045, 3339, 5049, 10659, 12441, 24871, 24969, 29029, 50065, 58435, 64285, 87685, 99693, 132957, 137885, 140335, 353133, 423657, 596037, 655707, 734517, 745503, 894387, 1390753, 1406427, 1529983, 1641783, 1739507, 1823877
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OFFSET
1,1
LINKS
Donovan Johnson,
Table of n, a(n) for n = 1..500
EXAMPLE
sigma(15) = 24 = phi(3 * 15), so 15 is a term of the sequence.
MATHEMATICA
Select[ Range[1936556], EulerPhi[3# ] == DivisorSigma[1, # ] &]
PROG
(PARI) is(n)=sigma(n)==eulerphi(3*n) \\
Charles R Greathouse IV
, Dec 09 2013
CROSSREFS
Sequence in context:
A027442
A208728
A219689
*
A328213
A271733
A280883
Adjacent sequences:
A074888
A074889
A074890
*
A074892
A074893
A074894
KEYWORD
nonn
AUTHOR
Joseph L. Pe
, Sep 13 2002
EXTENSIONS
Edited and extended by
Robert G. Wilson v
, Sep 17 2002
STATUS
approved
