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A069225
Numbers n such that phi(n) is the reversal of sigma(n).
7
1, 65, 2771, 10920, 158804, 2413091, 16636354, 117650080, 140766297, 630947067, 4639526938, 153896850898
OFFSET
1,2
COMMENTS
a(13) > 10^12. - Giovanni Resta, Nov 03 2012
EXAMPLE
phi(65) = 48 = reversal(84) = reversal(sigma(65)), so 65 belongs to the sequence.
n=2413091, sigma[n]=2528032, phi[n]=2308152=rev[sigma[n]].
MATHEMATICA
Select[Range[10^6], EulerPhi[ # ] == FromDigits[Reverse[IntegerDigits[DivisorSigma[1, # ]]]] &]
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Joseph L. Pe, Apr 12 2002
EXTENSIONS
a(6)-a(8) from Labos Elemer, Oct 22 2004
a(9)-a(11) from Donovan Johnson, Jan 14 2011
a(12) from Giovanni Resta, Nov 03 2012
STATUS
approved