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A072395 Numbers n such that reverse(phi(n)) = n. 4
1, 21, 63, 291, 2991, 6102, 46676013, 69460293, 2346534651, 6313047393, 23400000651, 80050617822, 234065340651, 234659934651, 2340000000651, 2934000006591
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OFFSET
1,2
COMMENTS
For all n, a(n) = reversal(A085331(n)), so see Comment on A085331. This sequence is a subsequence of A069215 and if m is a term of A069215 and 10 doesn't divide m then m is in this sequence. - Farideh Firoozbakht, Jan 09 2005
a(13) > 10^11. - Donovan Johnson, Feb 03 2012
a(17) > 10^13. - Giovanni Resta, Aug 06 2019
LINKS
EXAMPLE
reverse(phi(6102)) = reverse(2016) = 6102, so 6102 is a term of the sequence.
MATHEMATICA
Select[Range[10^5], FromDigits[Reverse[IntegerDigits[EulerPhi[#]]]] == # &] (* corrected by Harvey P. Dale, Oct 03 2011 *)
CROSSREFS
Sequence in context: A069215 A115921 A251808 * A113781 A299450 A300088
KEYWORD
nonn,base,more
AUTHOR
Joseph L. Pe, Jul 21 2002
EXTENSIONS
More terms from Robert G. Wilson v, Jul 23 2002
More terms from Farideh Firoozbakht, Jan 09 2005
a(10)-a(12) from Donovan Johnson, Feb 03 2012
a(13)-a(16) from Giovanni Resta, Aug 06 2019
STATUS
approved

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Last modified September 18 16:48 EDT 2024. Contains 376002 sequences. (Running on oeis4.)