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%I #12 Apr 22 2014 06:05:31
%S 1,24,26,87,168,388,594,666,1998,2688,5698,5978,6786,7888,68796
%N Numbers n such that phi(n) = product of the digits of n.
%C Sequence is finite because for n large enough phi(n) > n / (exp(EulerGamma) * log(log(n))+3/log(log(n))), while pod(n) < 9*9^ceiling(log(n)/log(10)). If a(16) exists, it holds 10^13 < a(16) < 10^64. - _Giovanni Resta_, Apr 22 2014
%D C. A. Pickover, "Wonders of Numbers, Adventures in Mathematics, Mind and Meaning," Oxford University Press, NY 2000, Chapter 72, 'Apocalyptic Numbers,' Pages 176 - 178.
%H C. A. Pickover, "Wonders of Numbers, Adventures in Mathematics, Mind and Meaning," <a href="http://www.zentralblatt-math.org/zmath/en/search/?q=an:0983.00008&format=complete">Zentralblatt review</a>
%e Phi(666) = 6*6*6
%t Select[ Range[ 10^7], EulerPhi[ # ] == Times @@ IntegerDigits[ # ] &]
%K nonn,base,fini
%O 1,2
%A _Robert G. Wilson v_, Dec 26 2000
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