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A104898 Numbers n such that phi(n)=phi(d_1)^phi(d_1)*phi(d_2)^phi(d_2)* ...*phi(d_k)^phi(d_k) where d_1 d_2 ... d_k is the decimal expansion of n. 2
1, 2, 34, 512, 34816, 421192, 1213173, 1311471, 2291616, 2622942, 7624162, 12333173, 13421568, 15221171, 27132646, 41134392, 49131264, 76142643, 121676464, 124127822, 143327424, 143942616, 149424426, 166467132, 194626614, 227826131, 417414464, 423432736 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Next term is greater than 3*10^8.

LINKS

Hiroaki Yamanouchi, Table of n, a(n) for n = 1..4065

EXAMPLE

227826131 is in the sequence because phi(227826131) = phi(2)^phi(2) * phi(2)^phi(2) * phi(7)^phi(7) * phi(8)^phi(8) * phi(2)^phi(2) * phi(6)^phi(6) * phi(1)^phi(1) * phi(3)^phi(3)) * phi(1)^phi(1).

MATHEMATICA

Do[h=IntegerDigits[m]; l=Length[h]; If[Min[h]>0&&EulerPhi[m]==Product[ EulerPhi[h[[k]]]^EulerPhi[h[[k]]], {k, l}], Print[m]], {m, 300000000}]

CROSSREFS

Cf. A103113, A058627.

Sequence in context: A180764 A228654 A005261 * A218432 A071799 A273052

Adjacent sequences:  A104895 A104896 A104897 * A104899 A104900 A104901

KEYWORD

base,nonn

AUTHOR

Farideh Firoozbakht, Mar 29 2005

EXTENSIONS

a(26)-a(28) from Hiroaki Yamanouchi, Sep 08 2014

STATUS

approved

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Last modified December 6 12:43 EST 2016. Contains 278781 sequences.