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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(13) > 10^12. - Giovanni Resta, Nov 03 2012

LINKS

Table of n, a(n) for n=1..12.

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

Cf. A000010, A000203, A004086.

Sequence in context: A217675 A237858 A075474 * A211960 A293695 A133853

Adjacent sequences:  A069222 A069223 A069224 * A069226 A069227 A069228

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

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Last modified June 16 10:03 EDT 2019. Contains 324152 sequences. (Running on oeis4.)