A135236 - OEIS

%I #2 Mar 30 2012 17:37:44

%S 1,2,3,4,6,81,234256,614656,1679616,24794911296,

%T 2518170116818978404827136,

%U 4301431178848799040411011070519998467949638490834092425216

%N Numbers n such that n=s^phi(phi(s)) where s is sum of its digits.

%C Next term has 96 digits. In fact the sequence has only 14 terms, a(13)=250^40 and a(14)=370^48.

%e 24794911296=(2+4+7+9+4+9+1+1+2+9+6)^phi(phi(2+4+7+9+4+9+1+1+2+9+6)) so 24794911296 is in the sequence.

%Y Cf. A135234, A135235, A135237.

%K base,fini,nonn

%O 1,2

%A _Farideh Firoozbakht_, Nov 24 2007