The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 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 (list; graph; refs; listen; history; text; internal format)
 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 Cf. A085331, A069215, A102278. Sequence in context: A069215 A115921 A251808 * A113781 A299450 A300088 Adjacent sequences:  A072392 A072393 A072394 * A072396 A072397 A072398 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified September 29 10:06 EDT 2020. Contains 337428 sequences. (Running on oeis4.)