OFFSET
1,2
COMMENTS
a(9) > 5*10^11. - Giovanni Resta, Apr 18 2014
a(11) > 5*10^13. - Hiroaki Yamanouchi, Aug 27 2015
EXAMPLE
The arithmetic derivative of 43910+2 is 69948, of 43910+1 is 39201, of 43910 is 30747 and 69948 = 39201 + 30747.
MAPLE
with(numtheory); P:= proc(q) local a, b, c, n, p;
for n from 1 to q do
a:=(n+2)*add(op(2, p)/op(1, p), p=ifactors(n+2)[2]);
b:=(n+1)*add(op(2, p)/op(1, p), p=ifactors(n+1)[2]);
c:=n*add(op(2, p)/op(1, p), p=ifactors(n)[2]);
if a=b+c then print(n); fi; od; end: P(10^9);
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Paolo P. Lava, Apr 17 2014
EXTENSIONS
a(7)-a(8) from Giovanni Resta, Apr 18 2014
a(9)-a(10) from Hiroaki Yamanouchi, Aug 27 2015
STATUS
approved