OFFSET
1,2
COMMENTS
a(10) > 5*10^12. - Giovanni Resta, Sep 16 2016
EXAMPLE
6’ = 5, 5’ = 1, 4’ = 4 and 5 = 1 + 4.
MAPLE
with(numtheory): P:= proc(q) local a, b, c, n, p;
a:=n*add(op(2, p)/op(1, p), p=ifactors(n)[2]);
b:=(n-1)*add(op(2, p)/op(1, p), p=ifactors(n-1)[2]);
c:=(n-2)*add(op(2, p)/op(1, p), p=ifactors(n-2)[2]);
if a=b+c then print(n); fi; od; end: P(10^9);
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Paolo P. Lava, Sep 15 2016
EXTENSIONS
a(9) from Giovanni Resta, Sep 16 2016
STATUS
approved