|
%I #11 Sep 11 2015 03:39:36
%S 12,32,44,332,5103,10935,12555,59049,69255,94041,185895,1114641,
%T 1265625,1453125,3639916,8015625,10475212,10521657,12254625,21515625,
%U 146484375,155649627,178598385,244603436,362087739,1408107267,1540368225,2186172700,2490234375
%N Numbers that are equal to the arithmetic derivative of their cototient.
%C Solutions of the equation n = (n - phi(n))’.
%C a(32) > 10^11. - _Hiroaki Yamanouchi_, Sep 11 2015
%H Hiroaki Yamanouchi, <a href="/A248817/b248817.txt">Table of n, a(n) for n = 1..31</a>
%e Cototient of 12 is 12 - phi(12) = 12 - 4 = 8 and the arithmetic derivative of 8 is 12.
%p with(numtheory); P:= proc(q) local a,n,p; for n from 1 to q do
%p a:=(n-phi(n))*add(op(2,p)/op(1,p),p=ifactors(n-phi(n))[2]);
%p if n=a then print(n); fi; od; end: P(10^6);
%Y Cf. A003415, A051953.
%K nonn
%O 1,1
%A _Paolo P. Lava_, Oct 15 2014
%E a(21)-a(29) from _Hiroaki Yamanouchi_, Sep 11 2015
|
