OFFSET
1,1
COMMENTS
Solutions of the equation n = (n - phi(n))’.
a(32) > 10^11. - Hiroaki Yamanouchi, Sep 11 2015
LINKS
Hiroaki Yamanouchi, Table of n, a(n) for n = 1..31
EXAMPLE
Cototient of 12 is 12 - phi(12) = 12 - 4 = 8 and the arithmetic derivative of 8 is 12.
MAPLE
with(numtheory); P:= proc(q) local a, n, p; for n from 1 to q do
a:=(n-phi(n))*add(op(2, p)/op(1, p), p=ifactors(n-phi(n))[2]);
if n=a then print(n); fi; od; end: P(10^6);
CROSSREFS
KEYWORD
nonn
AUTHOR
Paolo P. Lava, Oct 15 2014
EXTENSIONS
a(21)-a(29) from Hiroaki Yamanouchi, Sep 11 2015
STATUS
approved